EDIT 2: Thank you to everyone who offered advice! I called back BofA to make sure we had the investigation/case #, then called TD Ameritrade to tell them about the situation. Unfortunately, like some of you predicted, they weren't able to confirm anything with me because of security reasons, which I understand. However, they did search if there was any account with my mom's name and zip code or SSN and they told me there wasn't. This was what I was expecting anyway, since on the transaction there is a name there and she doesn't have any association with TD.
Since they couldn't really say if there was/wasn't an account with the information I gave them, I don't know if it's flagged for fraud or anything like that. I stressed to them that I wanted them to prevent that account from being able to do any more damage, so hopefully they understand.
We also did file a police report, changed her passwords to everything, made sure she had 2FA, transferred her money to another account, canceled her cards, documented everything ourselves and we should be getting complete documentation of everything happening from her bank in the mail. A lot of people mentioned filing a complaint with CFPB but I'm not sure if we should do that now or if a few days go by without any action or notification.
Other than that, I think we've done most of the things people suggested we do in this situation and like some said, we now need to wait and let the bank handle/investigate it. The people I did speak with yesterday said it was likely she'd get her money back but we won't believe that until we see it. Thank you again to everyone who gave helpful advice!!