You are not her employee. She is treating you as though she is your boss.

You provide a service - but you are self employed. You choose what you do and where you draw the line.

Snacks and toys in the stroller sound like a nightmare alone -crumbs in the seats, attracting bees and toys dropping every few min that you have to stop and pick up.

Nap time pajamas - WTH? It's only 1.5 hours. That's a lot of extra work for you

Nevermind that the behaviour is not good.

I think you need to take hold of the reins of your business and let mom know that you are in charge and kids and families have to follow your guidelines and rules