Good grief, you sending a snack for everyone is a kind gesture and if I was the recipient I would certainly appreciate your efforts. Even if you send a pack of cookies (and Maria cookies are not the over sugared ones) one day and then fresh fruit another who cares.

I wouldn't take it personal. Send another batch of goodies and if it comes back then don't send it anymore. If the other Mom has a problem with your generosity, then it is HER problem. Don't sweat the small stuff.