Partition and possession of ancestral property

My parents in law were expired without making any will. My husband have two brothers and he (my husband) is the younger one. The eldest brother also expired. There is ancestral property which is in my father in law name on records. but now the wife of eldest brother (who is widow) threaten us that she will kill us but not give our share in ancestral property. please guide any solution as per law as we want only our share and want to construct a different home because we are afraid to her. we have a daughter. my husband also suffering from neuro problem which can't be cure. he is under regular medication. the sister in law (who is widow) give threat that either she will kill us or if my husband dies because of his disease then also he make me and my daughter homeless by snatching our share. please guide me for me and my daughter future safety and security. we recently get our marriage registered also as a safety measure but we also know its not enough to deal with her. right now we are living in ground floor and she live in first floor of the same house.