Firstly, Malwarebytes is not normally an Anti Virus, just Anti Malware and as such is not equipped to deal with a Virus.
Then download this onto your own PC McAfee Stinger put it on to one of those little USB Drives and plug that into the Laptop. I have never had to use it.
Was he running an Anti Virus? If he was it will need updating or replacing, this is Free and as good as any AVG but do make sure that you download the Free one as they will try to up-sell if they can.
Make sure that there are not 2 Anti Viruses on the Lappy as that can cause horrendous problems, the least of which is that neither will work properly.
If that has done the trick, then a good tidy up with CCleaner, again Free, will not go astray.