If your machines are both running Win 10 (I don't know if all the following works on another OS), you can use "Quick Assist" - up to a point; you'll be able to remove files etc from mum's PC, but you can't transfer files etc from your PC to hers or vice-versa. That proviso aside, you can do pretty much everything on her PC that you know how to do on yours.
Both of you need to click the magnifying glass on your taskbars, start typing "Qui..." - now press "Enter" when "Quick Assist" goes to the top of the list.
joko - now you click "Give assistance" & sign in with your Microsoft details. You'll be given a 6 digit security code that you need to pass on to your mum - she'll have to input the 6 digit code & then allow you access (I can't recall the exact wording she'll see, sorry). Her screen will now show on your monitor & your mouse now controls her cursor.
You can simply move the cursor back to your own PC if you need to - it's important to keep her informed (I'm assuming you're on the phone here, that's how I use this facility...) as to what you're doing & if you need her to actuate something to move things forward.
I do this quite regularly & have achieved what was needed. It can be "weird", but it's a very useful tool when you get used to it.