My parents in law are in their late 80s and never used a mac before. My husband put them on his old 2010 imac running el capitan and they never looked back. If your mum uses facetime or skype, a camera/speaker setup might be a bit tricky on a mini. I tried 2 different cameras to find one with the least echo and also had to switch from built-in monitor speakers to speakers on the floor. My husband also has the new mini and he got the dell monitor u2718q for about $400 and he likes it as it has more built in usb3 plugs. I also think the basic model would work, especially if she has music, pictures, and files on the external. I did just that with spinning drives and it works well. If you create a data folder on the external and stick it in the favorites on finder it would make it easy to make sure it is used properly. I did end up relocating photos and itunes to the external. It wasn’t hard. Both of us turned off sleep and do not use encryption. I’m happy to say that both computers are working absolutely fine. Hubby replaced a 2013 imac at work and he loves the new system. I replaced a 2011 Windows 7 PC that was getting rather slow.
