high cholesterol is when you eat foods with alot of LDL in it, low density lipoproteins. HDL, or high density lipoproteins,are the good lipoproteins. So do your research and get your mom to eat foods that are rich in these nutrients.
And I can't stress this enough. Physical activity is a MUST, it stimulates 'reverse cholesterol transport' which transports alot of the bad fats that clog up in your vasculature into the liver where they belong. Even if she can't do vigorous level exercise, make sure she is able to do some walking at least. Walking out in the fresh air when done in the right amounts, can do alot of good for the body, and I can guarantee you that. 150 minutes per week in bouts of 10 minutes or more is ideal. Often times, people will underestimate the benefits that exercise can bring into their lives. People gotta start to realize that exercise is a long-term cure to a long list of diseases out there and inactivity is the actual cause of disease.
Alot of the diseases out there are genetically predetermined. But with the right amount of exercise and diet, many of these genes won't be turned on until much later on in life if at all, and consequences will be much less severe.
Back when I was a kid, I had asthma and exercise was what helped me overcome this at a very young age. Because of exercise, I never had the need to use a puffer, and eventually, I would no longer have asthma.
Of course, stay away from high cholesterol foods such as seafood, etc.
A link to a list of foods that I'd personally recommend:
Cholesterol: Top five foods to lower your numbers - MayoClinic.com