malwarebytes is very very safe and will not delete or harm any system files compared to some other programs out there.
You should install it and for best results once its installed and updated, is to restart your computer and boot into safe mode.
This is done as the computer is switched on and you tap one of the function keys.
It varies from each computer so you might have to try it a few times F4 F6 F8 F12 are probably the most common. Youll then see a list of options, one being SAFE MODE.
Let the computer startup once you select safe mode and run malwarebytes, any problems will be found in its quarantine section where you can delete them.
Restart afterwards and boot to safe mode again and run your antivirus.
This should rid you of any problems your having
Its possible she clicked on one of the many adverts that appear all over the web which is where these program types dwell. Just warn her about these and it shouldnt happen again. Facebook is probably the worst culprit!