My husband served his ex for custody

Ok here's the situation my husbands ex has been living from house to house since around April 2014 and now since January 21, 2015 my husband has had the kids full time because there mom is home less and we can never get in touch with her, she has primary custody of the kid's so she gets child support, she has been getting child support without supporting the kids so today we finally got a hold of her and we had to serve her for custody and we all got into an argument. Our thing is she doesn't have a place and she is getting paid for not taking care of the kids. Do you think we were wrong for taking her to court. What's would you have done?