Update

Well, I called M, left a message, and said to call me back ASAP and she did. I thought that was good that she called back right away (although I did mention we needed to discuss expenses and nothing more could be paid unless I spoke to her). I told her the agency couldn't pay expenses unless she goes to the agency in person, and that she has to bring valid receipts in for groceries (shampoo is okay, but not excessive amounts of it). She said they never told her she had to come in person and it's 4 flights of stairs and hot and she can barely climb, so I told her I'd ask them to meet her downstairs, and she was agreeable. She says as well that her car is completely dead and she is relying on her mom and sister to chauffeur her around, and I told her I'd check with the lawyer about taking taxis. She didn't seem overly keen on that idea, but I'll at least ask.
I also said she'd missed two appointments with the lawyer, and had to see the lawyer this week. She said she was busy with the agency all Friday and she couldn't see the lawyer, but I told her she had to call and cancel because the lawyer was expecting her. She said she would call and reschedule.

She said she'd take care of it all, and acted like a chastised child, but not mad at me, just a kid who realizes she's been bad and got caught. And we are pretty seriously thinking of hiring a private investigator to make sure she's not scamming us. I still don't think she is, and she's just young and flaky, but I also think she's told me half-truths several times.

So we'll see what happens.

ETA - Oh my, the poor thing. I called the agency. They're on the third floor. There is an elevator right near the stairs. M has to go up 6 steps outside, enter on the second floor, and then can take an elevator up one floor. Unbelievable, her excuses and exaggeration. Does she really think I won't find these things out??