Your mum will have a hard job concentrating on two things at once. The most important thing is to get her blood sugars under control.
Reducing total carbohydrate consumption, switching to lower glycaemic versions of carbohydrates that she does eat (less bread, pasta, rice, potatoes, flour, sugars processed food, fruit juices and more salads, green leafy veg, legumes, whole fruit) is the main dietary strategy to achieve this.
Upping her protein to at least a 3-4oz portion at each meal can help reduce hunger and the need to snack.
Adding extra virgin olive oil to salads and butter to vegetables helps the taste.
Eating more meat, more dairy, cream, cheese, nuts can be done when she has reached her goal weight or if she only has a little to lose.
Most people find the cholesterol pattern stablises out by itself on such a diet.