I agree with above, it's called CYA.
Now, here is a suggestions, on the back of the check go ahead and write, above where she will endorse it:
"Pay to the order of _________________________"
Put in the name of the treatment center. Then you can give her the check, ask her to endorse it and you will be happy to 'mail' it for her, or just give her the check. She will have no choice with the "Pay To" already on the back, because if she tries to change that, no bank will accept it.
You might also have the envelope ready, addressed and stamped, in case she gets upset.
But, you asked, and my answer is, I would not give my A that size check after only 45 days of treatment. No way, no how.
Please keep posting and let us know how YOU are doing as we do care very much.
Love and hugs,