re: So my wife received a call from one of our child's classmates mother

I would just let it drop and write her off as crazy. If the woman keeps it up or if your wife can't let it go, email the teacher and cc the principal. Parents are supposed to bring such concerns to the school instead of confronting parents as it creates more drama for the school when stupid people can't play well with others. They would then contact her and tell her to address her concerns to them instead if you. If she's a crazy helicopter mom, she wouldn't dream of messing with the principal as he can limit her access to the school.