I uploaded pictures for both of my parents (I ended up getting 2) and they have these digital picture frames by their bed and watch the pictures scroll on repeat. So, yes I think this would be ideal for your mother.
The only thing I would suggest would be to buy a SD card so you have the option to upload a lot of pictures.
I just got one, shows some jpegs but not others. I have not figured out the reason yet - it is not size. Possibly Dimensions?
edit - does not seem to be dimensions, either.
edit 2 - apparently there are 2 types of jpeg files, although I don't know how to tell the difference. Only "baseline" jpgs can be viewed by this device. Opening in MS Paint and resaving as jpg fixes the problem and allows them to be viewed.
my laptop has an sd slot. if your's doesn't buy a small adapter gizmo from walmart or pc shop or bestbuy that plugs into your usb slot. $15 at most. stick the new sd card and it into your pc and use windows explorer to copy them over. the smallest SD card will hold thousands of pictures for you to add more later. pay $1 per GB for SD card at most, ie 8GB is $8