How to contest a case against Domestic Violence and dowry?

My brother is married to a girl for two and half years, she is neither interested in taking care of my parents nor a joint family and did not come to living with my brother almost from the time of marriage and has filed domestic violence and dowry case on all the family members when my brother objected for a separate family ..We attended an inquiry by the police and both agreed to my brother's separate family. My brother took a new house and My mother is now living with me somewhere distant but still my brother's wife has not come to my brother and she has sent all of us the same domestic violence notice..challenging not to leave anyone of us happy she is proceeding with these kind of notices. I am more worried about my mother. she is diabetic and troubled with hypertension. Her health is becoming more worse after incidents like these.She is standing guilt for nothing.How to rescue my family?