I would agree that the teen's actions were not appropriate, but I wouldn't demand that my kid apologize to someone who has been acting, to put it mildly, inappropriately for a while. I might have the kid apologize to the hosts of the gathering, but frankly, if I had been letting this woman berate my elderly mother, to say nothing of her past record of making people cry, without at the very least absenting myself and my family from gatherings she was invited to, I think I would owe my kid an apology for letting things get that far.