You must use myether wallet, imtoken and trust wallet don't used any extension because sometimes their money got disappear or they are prone of hacking yesterday my friend sees his wallet and he sew a transaction but he didn't used his wallet that time he is using metamask then it was happen.
That's very vague to put the blame on metamask since the same thing could happen to myetherwallet too if your computer got compromised. If he using myetherwallet or metamask, he should know about all the risk.