Mental and physical harassment of my sister at ill laws place

I am writing this on before of my sister, seeking your help from you. Dear Sir/Mam My sister is married from last 10 years, her husband doesn't earn anything beside of his parents owned him a autoriskshaw . He doesn't go to work, fully depended on his parents as they work in London. He is fully controlled by his parents, he is not capable of doing any thing to earn money. His parents abuse her over phone even personally. They tired to hit her, even abuses by saying that she lays with someone else and her husband doesn't respond to any of their the allegation. They abuses entire our family, my father is not well and my mother helps him in his daily routine so they are not capable of fighting for her life. My mother and aunt once tried to resolve and discuss the problem but they were abused and bitten by her mother-i-law. His parents are not even afraid of police as they are powerful by money status. We are from the poor background we doesn't have any financially support. We are two sister staying away from our parents. She is everyday harassed by his parents and sister, accusing her about everything even about character. I am afraid of sister committing suicide with her children, she has no hope left. as she is weak and alone in that house. Her ill laws are very greedy harassing her about her dowry, ask her to with my parents and leave the house. they are very proud and fearless they are wealthy people. Please help me in charging case against them for harassment so that they can't leave India. Be present in all the case hearing if i raise a case against them. please help asap.