How to initiate legal steps for domestic violence and maintenance charges

My sister is being tortured and beaten by his husband from last 1 year. Married- From 9 years, but staying continously with her husband from last 1 year. As her husband quit his job in Saudi and returned back to India. Now, he started torturing and frequently beating his wife and children. He is asking her to give her jewellery and bla bla.. She and his two child is staying with us from last two months. We called him and his brothers to discuss, yesterday they came and started justifying tha