My opinion is that people need to make sure they get enough protein, rather than make sure they don't eat too many carbs.
I use the Zone percentages, which are 30:40:30 protein:carb:fat. I also try to aim for 70 to 100 grams protein.
Your mom's plan doesn't have enough nutrition or calories, IMO.
"My religion is kindness." --His Holiness the Dalai Lama