Son harassing mother

I am from Hyderabad. My grandparents have two sons and two daughters which includes my mum and an aunt who was a single mother and expired 2 yrs ago. my younger uncle once in a while starts fight out of nowhere and talks very abusively to my grandmother about her family and abuses my grandmother as well. There were incidents when he even beat her. My aunt's daughter has been staying with my grandparents since her mother's death. My uncle even beat her once. He is unmarried and unemployed. These fights have been gng on since my childhood and a few years ago my grandfather had even divided his property among his two sons. My grandmother's property has not yet been. As per my knowledge he was even beaten up by someone from my grandmothers family once for his abusive words and acts. As he can't do anything with them, he tortures my grandmother. No one is ready to file a complaint against him as people think that he might torture my grandparents more later. Pls suggest me what I can do? I'm 20 yrs old and I feel frightened to go to their house due to this guy. Pls help me