Not going to lie, I feel a System76 machine is way overkill for someones grandmother who likely doesn't really need that kind of horsepower... Especially given the cheapest model they sell is 1400.
minus the cost of supporting windows
minus the cost of malware and virii on windows
hmm, so that works pretty well, IMHO :-P
You can get windows laptops for $100–$500 just get one of those and put Linux on it? Not a single person's grandmother (except maybe that one that plays Skyrim) needs a $1400 laptop, total waste of resources.