My mom and grandma are using Manjaro. With grandma I'm the only one doing the updates of course, but with mom she usually can do it herself just using pamac-tray. If that fails a phonecall is usually sufficient. Once in a few years I have to come and do something by myself
And when that happens I work with a distro that just works, instead of some broken crap
EDIT: I tried having Mint on their computers. Big mistake, it's as broken as Debian and Ubuntu
EDIT: Xfce is very nice in such cases. It looks familiar for them while being manageable for me