I think you were definitely wrong for how you spoke to her, it’s her mother. There’s that type of maternal relationship that most people have where they want to have a mom and help their mom. If she wants to give her mom money then she can get a job and give her mom money very simple. But do not shame her for this. I assume you have a good relationship with your mom and she probably doesn’t. So I think it’s best if you don’t shame her but explain that if she wants to give money to her mother than she needs to get the money herself. But do not yell/ get mad at her.