Vegetables that are non-starchy, such as carrots, lettuce, spinach, squash etc are very good. Keep fruits
in the diet but watch for rises
in blood sugars. Drink lots of water if other medical issues allow(if your mother has heart issues she may not be able to drink lots of water).I strongly suggest meeting with a diabetes educator or dietician to review your mom's food choices and do some meal planning. It is much more comprehensive than I can offer in this post.
All the best.