Rights of mother in law

We were two brother and one mother living in self acquired property transferred to my mother name using relinquishment deed. I was married 8 years back and having two daughters and my elder brother got married last year. They both are government employees and having good salaried income from their jobs. She started misbehaving with my brother and my family after few days of marriage and spend most of the time in her parents house. My brother got expired two months back and now her wife and her family threatening my mother and my family . We have provided her all the things, his office claims and other ancestral property related thing without any objection. My mother is nominee in all things related to my brother financial things including his office claim and insurance policies. Now she has threatening my mother to sell out her house and give her share, otherwise she will false complains against us under domestic violence and other cases. My mother age is near about 68 years and she is mentally depressed after my brother death. She is still residing with her parents and visited our house anytime with his family members to show his presence in our house and placed her things in my brother room. She is trying to torcher my mother and my family by misbehaving. Can you please suggest me what I can do to safe guard my mother and my family? How can we restrict her to enter in my mother house? What she can actually do against my mother and my family by false allegation and cases. What rights she has in my mother property? Can my mother leave this house and start living in rented house to safeguard her from this mental torcher? Pls guide and help me out.