If the boy has missed several lessons by just not showing up (no call or email prior) then it appears that is status quo for that family. They obviously do not consider other people first. I would drop him as a student based on too many missed lessons.

As for her non-reply to your calls and emails she is just plain rude and inconsiderate. I know sometimes there can be circumstances where someone is unable to respond quickly and each case is different but this lady and her child have a history of being inconsiderate of your time.