False Elegations By In-Laws And Husband

My Sister who was married in 2009 under the Hindu marriage act have been harrassed physically and mentally by her in laws and husband from several years. She has been abused and beaten by them on the name of dowery and other matters. In april 2018 my sister called me while cyring. She told me that she has been beaten by her husband without her mistake. Me and my father reached to her in laws home next day. Upon reaching her husband, sister in law and mother in law all together abused us and faught with us. Even her in law mother slapped my sister in front of us. So i bring my sister with us thinking that the matter will solve in few days. But we never received any call from her in laws. But today i received an image on my whatsapp number from my sister's husband in which her mother in law have written an application to the police with all the false elegation on my sister like- 1. She harras and beats her mother in law 2. Pressurise her husband for the property 3. Abuse and threaten her mother in law to send her to the oldage home 4. Threaten to death What should be my next step. Kindly help.