If she has some use of her right side to help line up fabric pieces to get them ready to sew, then she could sure sew straight lines with a dual-feed Pfaff (integrated dual feed). Mine works much better than any walking foot I've had. For straight seams on reasonable fabric, you don't need to pin anything when using this machine. You might need to reposition a little on a very long seam (say, when inserting a 90" zipper) but a piece or two of painter's tape would take care of that. I don't know what these machines cost now or what the used market is like.
Again, if she has some use of her right side but not a lot of fine motion, an eraser stick might help her position fabric layers for sewing. A pencil with eraser end, or a big pink eraser, or a retractable white eraser (about pencil sized, black case with a long white eraser stick in it; office supply store).
Hope she can find something to keep busy and challenged but not frustrated!