Android - How can I remote support an Android tablet?
I attempted to get VNC options working, but they're all buggy. In particular the keyboard mappings and clunky and the screens never seem to render correctly. I even wrote to an author offering money for improvements but never got anything back.
Teamviewer 8 is the only solution I've found where it actually works the way it is supposed to (i.e. seamlessly). Teamviewer is free for personal use, which is a bonus, but it is by far and away the best solution I have found. It properly supports the Android home/nav keys and has complete and properly mapped support for keyboard input.
To use it, install Teamviewer 8 on your PC/Mac, and "Teamviewer Quicksupport" on your Android device. As far as I know, root is not required.
No, I don't work for Teamviewer.
As you already put it into your question: You might consider installing a VNC server on your mother's device. Admitted, most of them require root access, so this could be a problem. However, at least one claims to do without root: VMLite VNC Server. But it comes at a cost: There's no free version available, so you'ld have to pay about EUR 6.
To give you a closer idea, some quote from the app's description:
This app works on rooted and non-rooted android devices. However, for non-rooted devices, every time after turning the device completely off and on, you will have to connect your device to a Windows PC or Mac using a USB cable, then run a free desktop program, VMLite Android App Controller, to start the server on your device. Once the server is started, you can disconnect your device. If you don't turn your device off (but just let it "sleep"), then the server will continue running for months, if desired.
As that should definitely work, there are some other apps which might be working as well: VNC Server Ultimate¹ writes The app normally requires root but on some devices it works without root., so you could give it a try -- it's free, and a paid version is available for just EUR 2.
¹ VNC Server Ultimate was unpublished in 5/2015, so consider it a place-holder for the fact that "similar apps might exist"