What step has to be taken against physical and mental harassment

My sister got married in 2011.its been 5 years.They have a son who is 4 years old.Her husband has harrassed her physically 5 times.Recently My sister's mother in law used abusive words and her husband harassed her physically.she filed CRS in police station against him and his parents.Police has warned him and he has written and given in writing that he won't harass her again and he will send his parents to his hometown and they won't come back again.he own a flat and he has registered in his name.My sister sold her jewels worth 4 lakhs and helped him in buying flat.she is working and earns 20,000 and he earns 40,000.he has taken loan of 28 lakhs and pays 23,000 EMI per month.After giving in writing in police station his behaviour has changed.he drinks alocohol everday at home and tells i will behave like this only if you wanna stay you can stay or else leave. 1. What legal step has to be taken next if he harasses her again or continues doing the same thing?? 2. can she claim his property if she files divorce case?? 3. will she and her son get maintenance ?? Thank you