1. Since you are investing your hard earned money in purchasing a property you should carry out legal due diligence to ascertain whether the widow of owner of the land can sell the property to you. As the elder son of the owner is also dead his wife and children have succeeded to his share in the land. So the widow of the land owner cannot sell the property in the first place unless the widow of her elder son consents to the same. If the property is sold without the consent of the widow of the eldest son she may sue you on coming to know about the sale.
2. At first, you should find out whether the property is free from any encumbrance. This would entail making an inquiry as to whether the property has been mortgaged or not. If it has been mortgaged then it cannot be sold till the loan is repaid to the bank.
3. The title deed of the land and the antecedent title should be vetted to see whether the land was marketable and purchased against due consideration by the husband of this woman.
4. Whether the mutation has been carried out or not is also to be looked into.
5. Before you purchase the land you should make sure that electricity, water and other dues have been paid by the owner.
6. Last but not least, it should also be seen whether the property is the subject matter of any lawsuit pending in a court of law.
7. Take assistance of a local lawyer to carry out the above process of due diligence.