I don't think il ask for what she owes as it would probably turn into a massive drama.
She owes you money. The fact that you think it'll be a massive drama if you ask for what is yours tells you all you need to know about this "friendship". True friendships have respect and a true friend would be keen to repay their debts.
From now on when I meet her I'm going to take a small amount of cash for myself and no bank card.
If she asks for anything I'm going to say I don't have anything spare.
It's not the first time she's done this but I deffo will make sure it's the last.
Whilst I'm glad you're making sure it's the last time she steals your money, you shouldn't leave yourself short or put yourself out for this.
"No, pay for it on your card"
"No, go to a cash machine"
"You need to get this because you still owe me from two occasions recently."
"What do you mean you don't have enough to buy something for your mum, you brought £70 with you! I'm not your bank, obviously you need to spend within your limits."