If your husband give living expenses to her (your 99) monthly, then ask her to pay for herself.
If your husband haven't given $ to her, then I think even you pay for her daily (e.g. $100 each time), there are only 3k per month. It is less then the living expenses your husband should pay for her.
My 99 also doesn't know econ is very worse. She went to a few long+short haul trips in these 2 mths. She normally expects my hubby to treat her, however, as econ is that worse, my hubby only gave her a few hundreds for petty cash, she paid all the trips herself.
You should tell your 99 abt your finance situation. You are a 1 big family ma, she would understand.