Suggestions for a fun hobby for someone w TBI?

I need to know more about your mom, like what she did before the TBI. Does she have a backyard?

My Mother had a stroke at age 52. Before the stroke she had many hobbies and was active in the community. One of her hobbies was ceramics. She would paint them and give them as gifts. After recovering from the stroke she switched to tole painting on wood. Often she would use a stencil and then a brush to add detail. She used both hands on the brushes to control it.

When using a computer with a mouse she had to use both hands on the mouse.
I don't know why I never tried to get her to use a better input device. There are many alternatives to a regular computer mouse, touch screen, stationary ball control, Roller Mouse, The Pen Mouse, The Vertical Mouse,
Finger Trackball Mouse, Trackball Mouse, or Track pad.

https://www.flintrehab.com/activities-for-brain-injury-patients/

Some of these suggested activities are realistic; others aren't.   I think painting and dancing (check out Dancing for Parkinsons' Disease) might be the most appropriate. 

Some of the OT activities such as fitting round pieces into round openings, triangular, rectangular and square pieces into comparable openings might help, especially if they're multicolored pieces and can be interchanged to create colored patterns.

Does she want to do anything else?

What about Audio Books? I like them when I am doing other activities. I know it is not an activity, but it is a change.

Many folks here have their LO sort laundry, fold if they can.

Sorting and labeling photos is another task. You may have to do the labeling for her, but she could sort them out.

Do you have an ad blocker on the computer? It does not get rid of all the ads on FB, but it helps.

Would she be interested in coloring? They make adult coloring books now. Tear out the page and tape it to the table or onto a clipboard. She only needs 1 hand for colored pencils and could use an electric sharpener if she can remember how to use it.