This is not for me but for family and friends who are mostly oblivious to privacy issues. I can generally steer them towards more privacy orientated software but not for anti-virus/malware. I know prevention is better than cure and altering behaviour to avoid them to start with is the best defence but I cannot for the life of me understand how some family end up with so damn much malware on their PCs. They're not going to change their behaviour any time soon, if ever. So antivirus it is.
Apart from ClamAV, is there any anti-malware software that respects privacy? Paid is fine (since most are already paying anyway).
uBlock Origin on Firefox (and their browser of choice, if necessary). Preventing scam websites is a useful preventative measure that you don't have to monitor.
Maybe have remote support software set up on their computers set up already. Something scammers don't like to use.
Other thoughts:
I know this isn't exactly what you're asking, but if you can get your family/friends to know to never download a program or call a phone number... Or better yet, get them to simply reboot their computer, a lot of pain will be averted.
I wonder if there are ways you can manually lock down the computer that would also help.
One tool I install on every computer I work on is Unchecky. It automatically unchecks all of the "install bullshit Spyware" boxes when installing programs.
But, really the best option is to make them a user account that can't install software. Windows Defender is actually pretty good if the user doesn't have admin privileges.