Brother's wife harassing my mother. What option does mother have?

I have 2 brothers and one elder sister. My father passed away. He has his own self made property. He made no will. My brother's wife is always harassing my mother and some times she also physically abuses her. What action can we take against her? My mother is old and brother refuses to take care of her. Can she do anything? She wants them to quit the house. What options do my mother have?