My mom has a business and mostly uses Windows and Mac OS X; I mentioned Linux because it could help save money.
She is unfamiliar with Linux though; I gave her some basic introduction (uncertain if it’s any good, but sure), but I would like to be able to ease her into Linux if she prefers it.
I think you should pick a good desktop OS like Linux Mint, and install it and just put it in front of her.
I would avoid complex presentations about what Linux is and stuff like that because that can introduce all kinds of nuances that aren’t strictly necessary to know, which can scare people away.