I would recommend providing them simple instructions to boot in to safe mode and run the following scanners.
hitman pro
mbam
superantispyware
comodo cleaning essentials
I have put the scanners in that order for a reason. mbam seems to be the best at repairing the exe file association after removing fake avs.
to help verify the machine is clean comodo cleaning essentials has a program called killswitch. it has a whitelist of known programs and if you go to the view menu you can tick hide safe processes. that option saves alot of time. its easy to identify malware when only unknown processes are shown.
the file menu has an option to kill all the unsafe processes which will make running scanners much easier. finaly it has options under tools called quick repair which allows you to repair system tools such as task manager,run, system restore ,windows update etc.