I’ve never really used Ubuntu, but I’m going to agree with others here. If its what you use, it would be better in the sense that it would be much easier for you to give her phone assistance when she needs it, rather than giving her something you’re not used to and possibly having to go over and troubleshoot for her.

If she wants something more in the line with Windows, you could try Kubuntu, but I think the rigging behind KDE is pretty complicated for a casual user. You may want to help her set up the way she wants her desktop to look at first if you go this route. The only other Windows-like desktop is Cinnamon, but Cinnamon-Wayland is still in alpha and once they officially drop it that could make more work for you later.

Admittedly, I have 0 experience with the Unity DE, so that’d be your call if you think you can familiarize it for her.

Linux Mint or Debian running Cinnamon DE. Stable and predictable.

I put my mom on Linux Mint Cinnamon (Ubuntu based) looks a lot like windows with minimal bells and whistles. Mostly just works unless you have bleeding edge hardware. Most Ubuntu flavours should also work. I’m suggesting Ubuntu based distros due to the fact that most media codecs, fonts and drivers are installed or easy to install.

I had first installed Mint on my Dad’s laptop, but then switched to Fedora KDE after a while 'cause wayland has better security than x11, and then now running an atomic distro called ‘Secureblue’ (KDE) on it while disabling confinement of user namespaces for Flatpak applications. All this while, he didn’t find any trouble switching over from one to another.

PS. I’d have stayed with Mint if Wayland worked on it.

Seconding and thirding the use of an immutable OS. I specifically like Bazzite Gnome. People know it for gaming, but many don’t know it has a fantastic desktop mode, suitable for children, mums and grandmas.

Almost all the software a casual user needs is available from their Flatpak App Store, and it’s pretty as hell (looks very Apple-like and shiny). I have been using it for about a year and I am still impressed how fluid, polished and solid everything feels.

Use the exact same setup you have, then when she calls and asks you how to do something then you either already know or can check on your own machine!

I recommend LFS. It’s the most user friendly distro there Is.

In all seriousness, a Ubuntu derivative is gonna be the easiest, mostly because it’s what you use OP

It uses X and not Wayland

I moved my mother to Mint a few months ago. I have not had a single tech support call. She uses it daily. About a week in I asked her how it was going. She liked that printing worked more reliably and wished the scroll bars in Facebook were a bit thicker. Her printer used to show as offline sometimes in Windows but that issue has gone away under Mint. I was going to look for a theme with thicker scroll bars but she told me not to bother.

Granted she was a Firefox and Thunderbird user already so that helped with the transition.

Ubuntu. Simply because you use it as well. You will be the primary tech support. So something that you are familiar with is important.

If her router supports it I would set up a VPN and ssh on her computer so that you can help her. Maybe RDP or Sunshine/Moonlight as well.

Zorin OS

My mom was not interested in the surface cause she only need Mail, Browser, Whatsapp web and here Background image. So she used Ubuntu with the side bar as good as with Mint. Same goes for gmy Granny. I propose, Ask what possibilities are important for here - Do not ask about Application - and show here afther that where to do things.

For showing the new PC. Do it with some work she has to do. Learning curve is way better thatway.

I installed Debian on my dad’s laptop recently,

Ubuntu all the way

My grandma got along with Mint for Facebook browsing and KPatience.

If your mom is more into using real apps, plus the Windows UI, and you’re comfortable with some setup, I’d highly recommend Debian 13 with KDE Plasma and Flatpak, with the Flatpak-Discover integration. That’ll allow her to use lightweight, stable apps from apt, or more recent, but larger apps from Flathub, and install it all herself through Discover. Honestly, there should be a distro for that.

I’d be using that myself if it weren’t for some very specific software I need from the AUR.