She recently found out she's on a prohibited persons list for firearm purchasing. In order to get off the list, she needs the sign-off by a licensed clinical therapist. So, be warned, don't ever joke about that.
She doesn't need a sign off from a therapist, she needs a lawyer.
(and sadly, the money to pay for one..)
One of the biggest abuses of the law in current times is the placing of people on the prohibited list WITHOUT following the procedure set in law. To be legally deemed a prohibited person for reasons of mental health REQUIRES adjudication by a court. Putting someone on the list without that is (as far as I can see,) illegal.
Likewise, I would expect removing someone legally put on the list by a court would also require a court to make that decision, NOT a sign off from a therapist.
From here (and without any additional information) it looks like her rights are being violated.
Now, her addiction issue might be the reason, but there are specific rules about that as well, and it is also possible that those rules are not being properly followed, either, again, putting her on the list without proper due process.
Being PERMANENTLY DENIED a Constitutionally enumerated right, without due process (as spelled out in law) due to a chance remark, or any other reason, without the due process of law, is simply wrong.
I realize that many people want to avoid the risk that someone might do something harmful, and I agree that keeping guns (and other things) out of the hands of unstable individuals is desirable, but there is a process for that, in law, and not following it is violating people's rights.
If you feel the process in law doesn't protect us well enough, get it changed. But until then the law needs to be followed, as written. Good laws, and bad laws, the same applies.