Your wife should go to the Zürich Integration Deparment in Stadelhofen 7, they have a Curse für frauen, and the cost is less than 500 swiss francs per semester. They also offer child care while the mom's are in classes. They will interview your wife to check the level of german she has so she can attend the right class for her. It's a really nice enviroment with good teachers for intense and regular courses, and they have several "german schools" around the city ( i guess maybe other citys/cantons might have these too) Good luck!