I'm the odd one out on the PJ's LOL...I even change some of them if I feel they are in uncomfortable clothes for nap. The parents don't ask me too, I just do it out of my own preference. I don't want to nap in jeans so I don't make them lol. Anyways that's besides the point.
It's your daycare so your rules. (just a pet peeve of mine....I am not a babysitter so I don't expect parents to treat me like one)

The aggression itself would be enough for me to terminate but mom's attitude wouldn't help. I would write up a note explaining why you are terminating. I have physical aggression as an immediate termination in my contract but if you don't, I would give her the notice that was agreed upon. She won't be happy but so what...YOU WILL!! and that's all that matters in this situation. You have to look out for yourself and your son and the other children in your care. Be strong!!