Just to add to what others have said.
If you’ve had a virus, run a scan with Malwarebytes to double check it’s gone.
Make sure that she’s running the latest versions of Flash and Java, or uninstall them. Educate her regarding the auto-update features of these two apps.
Consider giving her a user account rather than an administrator account for day-to-day usage. Definitely give the kid her own standard account.
Some form of bare metal backup might be useful here. “Your PC’s broken? Never mind, I’ll press this magic button and ten minutes later, hey, perfect!” Of course, you’re already backing up her data, right?
Look into the nature of the infection she’s had. Depending on what it is, a format and reinstall might be safest.
Take seriously anything that involves keyloggers. There may be a very real risk that any online accounts accessed whilst the infection is present have been compromised. This includes her bank account.
Paying for AV may, but does not automatically, imply an inherently better product.