You can go as per the Indian Succession Act, Class II heirs list and Ask to court for Legal heirs certificate or LOA.

Plus get the Society Share Certificate transferred on your name, so the property will get transfer on nominee's name.

If you require any further details do let me know.

nominee of a property does not automatically become the absolute owner of the property after the death of the original owner. 

The inheritance shall be governed by Section 15(2) (b) of Hindu Succession Act 1956 wherein in the absence of any son or daughter the property shall devolve upon the heirs of the husband. If there are no heirs of the husband in Class I, then the property will go to Class II heirs. In case of no Class II heirs of the husband, the property will devolve upon Agnates, and if no Agnates then upon the Cognates.

Coming to your specific question, the property gets inherited to the heirs of the husband by default and there are rarely any cases wherein the whole lineage at the husband's side gets exhausted. 

In such cases, wherein there is no lineage of the husband at all, the property gets devolved to the heirs of the wife in the same sequence as mentioned above, i.e. Class I heirs > Class II heirs > Agnates > Cognates

1) nominee is only trustee for legal heirs 

2) share in flat inherited from husband would devolve on husband legal heirs ie husband siblings on demise of widow 

3) apply for letters of administration from District court for flat 

4) notice would be issued to legal heirs 

5)if no objections are received you would get LA in your name 

After death of husband, wife nominated sister’s son and sister’s grandson to flat of society jointly purchased by them. After the death of wife dying issueless, who will inherit the flat? That is you question. Sister’s son and her grandson share half of part. Half part will go to relatives of husband in following  order—

1. Brother’ son.
2. Sister’s son.
3. Brother’s daughter.
4. Sister’s daughter.
5. Father’s father, father’s mother.
6. Father’s widow; brother’ widow.
7. Father’s brother; father’s sister.
8. Mother’ father; mother’ mother.
9. Mother’s brother; mother’s sister.

Letter of administration is authority by which  an administrator is authorized by court to have the charge and administration of the property of intestate/person dying without making will. It is not an affidavit. it is applicable in your case.

situation where a married Hindu female dies intestate leaving behind her self -acquired properties. We shall assume she had no issue and was a widow at the time of her death. As per the present position of law, her property would devolve in the second category i.e. to her husband's heirs. Thus, in case the mother of her husband is alive, the deceased Hindu female's entire self-acquired property would devolve on her mother-in-law. If the mother-in-law is also not alive, it would devolve as per the rules laid down in the case of a Hindu male dying intestate. Thus, if the father of her deceased husband is alive, the next in line to inherit the property will be her father-in-law, and if the father-in-law is also not alive, then her property would devolve on the brother and sister of the deceased husband. Thus, the entire self-acquired property of the Hindu female would vest in the brothers and sisters of the of the pre-deceased husband and not that of the Hindu female even if she has siblings that are alive.

Therefore, where a Hindu female dies intestate leaving behind her self-acquired property and in case where her heirs in the first category fail, her property would devolve totally upon her husband's heirs who may be very remotely related or probably even unaware of each other's existence.

The wife is having 50% share in the flat and other moveable assets 

The husband died prior to her demise and so his 50% devolved on the wife (I am assuming that when the husband died, his mother was not alive)

Upon death of husband, his 50% share would devolve on his mother, widow and children equally under section 8 of Hindu Succession Act read with Scheduld I

Here assuming the mother of the husband predeceased him, and in absence of any children, the husband's share devolved on the wife 

Thereafter the wife died 

Now she had her own 50% share in the flat plus the 50% which she inherited from her husband 

Thus in absence of any children her own 50% share will go to the heirs of her husband under clause b of sub section 1 of s. 15 of Hindu Succession Act 

Further the 50% that she inherited from her husband would also go to the legal heirs of her husband as per clause b of sub section 2 of HSA 

Thus the entire flat would devolve on the legal heirs of the husband 

As there are no class 1 legal heirs of the husband (who are his mother, widow and children) the property will devolve on his class 2 heirs 

I assume that the father of the husband is no more

Father of husband is a class 2 legal heir under Entry 1

So the property will go to the siblings of the husband who fall under class 2 entry 2 (ie brother and sister of the husband)

The siblings of the wife cannot claim any right 

As there is a nomination left in favour of the wife's sister's son and his son (I assume that nomination is for the entire flat) the property can be transferred to that nominee 

However that nominee will not hold the property as an owner but only as a trustee for the siblings of the husband 

The letter of administration cannot be applied by the nominee but by the siblings of the husband 

The LA holder has to transfer the property to the legal heirs of the deceased ie the siblings of the husband 

Getting a LA is a lengthy and an expensive procedure 

It requires payment of court fees of max Rs 75k depending on the value of the assets

Plus there would be lawyer's professional fees and clerkage 

The LA application has to be filed as a petition in the Bombay High Court 

If the LA petition is filed by any one sibling of the husband with consent of other siblings then no notice is required to be given as all legal heirs would consent for grant of the LA

It takes about 8 to 10 months to get a LA grant 

In the meanwhile the LA applicant can apply for appointment of an administrator who can take care of the property until the LA is granted 

Dear sir/ma'am,

As per Hindu Succession Law, the property should go to Class 2 Heirs that is the relative of the husband. The siblings of husband

However as nomination is filed in favor of wife's sister, You can file petition in the form of LA application in the Court. Thank you.

- Section 15 of the  Hindu Succession Act states the general rules of succession in the case of a female Hindu , and it gives an order of priority for the devolution of the woman’s property which is –
Explains the devolution of the woman’s property as per the following priority:
1. First preference to sons and daughters, including children of any predeceased son or daughter, and the husband;
2. Heirs of the husband;
3. Father and mother;
4. Heirs of the father; or
5. Heirs of the mother

- Apply for getting Letter of administration before the district judge .