Your mother has to learn how to "protect" your/her belongings too.
when I have strangers, guests, workers in my house, they're allowed to be in certain rooms only.
They're not free to walk around as they'd like. (for my belongings and safety)
For some people like workers, I even lock the rooms.
Small young kids are not allowed in my house. (only from family & friends) If they scratch the wall, leather seats or break the stuff,
I know parents wouldn't want to pay for the damage. So I always provide seats for worker kids to sit, play, eat
outside in the garden or parking area. They're free to do what they like while I do business with their
parents. Just give them some old toy and snack.
I wonder if those parents could afford to pay you, even in an installment payment.
hope you find a good solution.