If she can open the registry (regedit) look for this key. Delete any keys related to AVG,Chrome, or any program that should be able to run.
If there is a working computer at the library you could download a portable browser and use it. But, there is always a possibility the flash drive could become infected.
Portable Firefox. Double click the exe file and expand the contents to a flash drive.
If the Portable Firefox allows the downloading of programs then I would recommend starting a thread in the Virus Removal Forum after reading what logs to post after reading the pinned posts. It may take some time to get a response.
If removing the registry keys allows Chrome to run or the portable Firefox allows access to the web then I would suggest first running a scan with HitmanPro. It has a free 30 day trial. An internet connection is required.
If a USB flash drive and another computer is available then you can download
Adwcleaner and run it.