My brother and his wife is torturing my mother

My mother is a retired headmistress from a reputed central government school. She is 70 years and still managing everything. She has her own HIG house, a car,and other investments .my brother who is 8 years younger than me,(36 years) and her wife is living with her. Both are working and earning well. But from the day he got married to this girl, both are harassing my mother mentally, physically and emotionally. She is tortured everyday, they abuse her, beat her. We did police complaint also but nothing worked.He just want her property and my mother is tolerating everything just out of motherly love. She is so confused to take any decision.They live in Delhi and I (daughter) live in Chandigarh .I am feeling so helpless. Everday I get phone calls from my mom about their torture and still she is not taking any decision. I am scared and concerned about her safety before something bad happens.