IMHO, If you have an income stream that supports it, then the answer is not "a side business". It's "go to school for something she wants to do better". And if taking care of the kid doesn't give her a chance to leave the house, the answer is "online classes and night classes when you're home to take care of the kid".

(If the thing she wants to do better is "draw" then here are some super awesome free drawing lessons from a master animator: http://johnkcurriculum.blogspot.com/2009/12/preston-blair-le... )