Employment Law Questions? Ask an Employment Lawyer.
She could attempt to allege harassment by the staff as a basis for quitting, so that she can then try to get unemployment. That is one concern, but she hasn't really been there long enough to establish that claim. She can allege it though, so it's something you'd have to respond to when the unemployment commission calls.
She can also try to claim disability discrimination, as she is now stating she is depressed, but that also would be very difficult to establish, as all the complaints about her surfaced before she made you aware of this potential disability. Again though, she can allege it to the EEOC and that will require effort on your part to respond to.
Finally, she can try to file a WC claim, alleging that her disability was caused by or increased by her working there. That would also be very difficult for her to establish based on a very short time frame. Again though, there would be effort in defending such a claim.
Do I think that your efforts in defending the claims would exceed the effort of keeping her employment? Not likely. For you, on these facts, you'd be in a very safe legal position to release her now rather than taking even more time to try to continue establishing more reasons to fire her, while she is establishing facts that might support her too.