Case on my brother, Case names me and my wife for domestic violance

Case filed from my younger brother wife side for Maintenance and domestic violence. Me,my parents and wife's name is there in case. She is resident of Ranchi and case is filed there although marriage is done in Ghaziabad. The marriage is done in 2015 and for first 6 to 8 months both brother and his wife stayed with us after that they left us and moved to Hyderabad and then Bangalore. In year 2019 she filed the case. My brother wife is currently working in MNC and due to all this my brother has to left his job and currently he is jobless. He is in depression due to all this. Actually there was no violence its all false case in which she pulled me , my wife and parents.When crime is done in 2015 why she waited till 2019. I want to remove my , my wife's and parents name from this suit and put a defamation suit on my wife's name. Please suggest the feasibility and probable time frame for the defamation suit.