Legal action against husband & in laws for physical & mental torture

My sister is married to a lawyer. During marriage in 2003, both the bride and the bride's parents were assured that the new house recently built is for the elder son (bride groom) and his to be wife and it will be in their name. After marriage, and expiry of Bride's father, they have started torturing her mentally and financially.They keep on asking her money (Salary income) in cash. It happened for good 13 years and she silently paid for every house-hold expenses and maintenance. No proof of payment as it was always collected in Cash from her. Now when she has stopped making payments, she is being tortured physically and mentally. She is being asked to vacate the home she is living since marriage as they claim it belongs to her in-laws (parents-in-law) and has no entitlement to live there. She is being asked to move out on a rented accommodation. The husband, who himself is a lawyer, has threatened of dire consequences if she does not. What should she do to live in same house?