Does my mother have share in her father's ancestral property?

My mother is a widow.I am the elder son My grandfather i.e(my mother's father) has a lot of agricultural land with him that was given to him by my mother's grandfather After my father's death we were financially struck and had to move to my grandfather's house (mother's father). He barely gives us 3 times meal a day. My grandfather has 16 cr worth property When my mother asks about property she is abused and often pushed and beaten. Please advise if I being the grandson or my mother can take legal action to get the property legally because these guys have made our lives a living hell.