This is 100% scam. Not only did your Mom lose money which she probably won’t ever get back, the scammers may have installed software on her computer which allows them to access it at anytime, without her knowing. This means her computer and her life is totally at risk. Even if she changes all passwords on all accounts, the scammers will find out what those are. By now, they have acquired total access to ALL online accounts.
The only way to fix this is:
(1) Take your computer to a local professional, tell them what happened, and have them do a thorough cleaning. If possible, the computer should be restored to factory settings. I realize this might not be desirable, so do what you can. Or toss the computer and buy a new one.
(2) AFTER this cleaning, contact your bank(s) and all credit cards to cancel and re-issue all. Follow your bank’s instructions. Change the passwords for ALL online accounts, even if they are not financial ones.
Last advice: Learn not to be gullible. Just because someone makes a claim does not mean it is true. There are crooks everywhere. Verify with trusted sources (no, not the ones that say, “You can trust us!”). Check before action if in doubt.