Clarification on grounds for tax exemption for sale of land by widow

Actually my mother's elder brother sold 10acre land to another person without knowledge of my mother and her 2 sister. My mother file the case against the person who bought this land. At last the person acknowledged the legitimate and legal rights of my mother and her sister's. Compromise was reached to pay market value rate of 2 acre to my mother. The person is saying I will deduct tax and give the amount. My mother is widow. Is their any provision in law for tax exemption for widow. If yes than what my mother has to do in terms of producing document. The amount to get is about 15 -16 lack.