Tell your mom she needs to buy Kale if she's going to buy all healthy foods.
Also, there are meats that are perfectly healthy. Like Salmon and Tilapia. Chicken, too. Eggs are also extremely healthy, the whole egg, not just the egg whites.
Wheat isn't really healthy, as it contains gluten, which is a very common irritant. I mean, whole wheat is a hell of a lot healthier than say...white bread or wheat bread (there is a difference between wheat bread and whole wheat bread). Whole grain or sprouted grain bread is better in general.
Spices and herbs are also your best friend, they are very healthy, they don't really have any calories, but keep to spices and herbs that are lower in sodium. And what spices you use really depends on your tastes. I love coriander and cumin, red pepper flakes, cracked peppercorn. Those are my favorites. Stay away from season-alls, though and meat rubs and creole seasoning, things like that have a s**t load of sodium.
And don't be afraid to try things you think you might not like.
OH And look into Daiya cheese, if your mom is really into the vegan thing, it's vegan, it's healthy and it's probably the best cheese replacement on this earth.