Legal heir certificate does not require. She must be having marriage certificate, sufficient to prove relation of husband and wife. Directly apply for compassionate employment. Only is entitle to this job.

Brother is not dependent and her mother can claim some % from salary or pension. 

And if government, not agree, file writ in high court. 

And for issue of LHC, consent does not require of any family member. 

In Kerala, the legal heirs of a deceased male Christian, if he died intestate (without a will), are determined by the Indian Succession Act, 1925, and the primary legal heirs include the widow, children (sons and daughters), and in the absence of these, parents, siblings, and other relatives.

Since you are the primary legal heir, you don't require the NOC from his mother or other extended relatives. 

The spouse is considered the sole legal heir in this scenario. The Indian Succession Act, 1925 governs the distribution of property in such case.

If the Tahsildar is delaying the issuance of certificate without any valid reason, you may approach District collector with an application seeking direction to the Tahsildar in this regard and his intervention.

As the husband was a government employee, all his official records would reveal the wife's details. Why do they insist on a legal heir certificate for giving her a job on compassionate basis? The legal heirs certificate issued by the tehsildar should list out all the legal heirs of the deceased in accordance with their personal law (in this case, Christian). If the tehsildar is not helpful, the wife can complain to the next Revenue authorities, including the District Collector. 

On demise of husband wife and mother are the legal heirs 

2) no objection certificate is necessary for obtaining legal heir certificate in wife name only 

Wife is first legal heir to husband, not brother or mother. Even if Tahasildar rejects to issue legal heir certificate  to wife, she is entitled to job on compassionate ground. Against delay by Tahasildar you approach Deputy Collector.

You can file complaint to his superior about the delay and seek certificate 

- As per law, after demise of husband , his wife and mother can be named as beneficiary 

- Further, as per Supreme Court,  compassionate appointments are not a matter of right but are exceptions to the general recruitment rules. They are intended to alleviate immediate financial hardship faced by the deceased employee's family

- Hence, the wife is first entitled to get the job on Compassionate appointment. 

Dear Client,

1. According to Hindu Succession Act, the mother and wife are legal heirs; brother is not a first heir. The wife is entitled to compassionate employment even without others' approval.
2. Tahsildar's Role: Tahsildar can give the legal heir certificate mentioning both wife and mother—no consent letter is necessary as per law. Delay is not justified.
3. Next Steps: Complain to the District Collector/RDO, or file a writ petition in Kerala High Court to order the Tahsildar to issue the certificate at the earliest.