Not sure if that is an option for you too, but I have a scanwatch light myself. It is a hybrid smartwatch, being a classic analog watch with a small black and white display in the background.
The scanwatch products are health focused, allowing the user to track a variety of health stats like heartrate, activities and sleep analysis. It is very energy efficient, requring a a recharge about once a month in my case.
It is noteworthy that the hybrid concept makes some cuts to the smartness of the watch, for example replying to messages from the watch is not possible, only reading them as they come in. It doesn’t have touch functionality either, instead you control it with the bezel.
You can configure in the smartphone app which apps are allowed to relay notifications to the watch, giving you the option to filter out most noise that is not relevant to your mom. You can also set up activity plans to track and/or remind her to engage in some moderate activities like taking a walk.
Do note though that the watch asks for a subscription for some premium functions, like workout plans and more in depth health analysis. I don’t have that myself either though, being able to generally monitor my activities is enough for me. The watch also relies on the paired smartphone for its gps functionality, without the phone it would essentially be reduced to a classic wristwatch.