What to do if nominee denies the agreement

My husband has died.He was a govt employee.I & my inlaws made an agreement for dividing all the death benefits of my husband into50:50. Now whatever I get from the office it was distributed between inlaws and me.But as in Nps my father in law is nominee, he denied to share with me that amount i.e13 lakhs. NPS was also mentioned in that agreement paper. He kept my husband's all personal Bank related things like Passbook and bank cards.As he is not giving me that share I also denied to give declaration affidavit to the office that I will take care of family members of deceased employee.My father in law retired as a Pharmacist of a reputed Tea Estate.He is a pension holder + He gets rent against his Pharmacist certificate + rent from house. But still he denies the agreement to share the money. 1: Is it compulsory to give such family declaration that I will take care of the deceased's family members ? Or I can get the job under Compassionate ground without the?