I suggest you both to communicate and understand one another.
As a wife, probably you can help to remind him that the main responsibility of a husband is towards his wife.
This is based on Islam.
Nafakah is to be prioritised to the wife, kids and then his mum/family.
His mum has her own husband that should takes care of her.
His father is responsible for the mum’s expenses etc.
It’s not wrong for your husband to give some money to the family and it is such a good deeds, but he must remember that his first priority is to the wife. If he gives it enough for you, and he has extra, then he can always give some to the mother as well.
Communicate with him. Get the mutual understanding.
Maybe on his side, there’s anything he wanted you to understand as well. So, yeah probably try to communicate and understand each other first.
Then discuss for the best solution among you both 💖
Emiey Gringer