I'm a fruit freak type 2 OAP on a low carb high(er) fat diet and you are able (and recommended! ) to eat some fresh fruit on this - berries are the ones usually recommended: generally strawberries, raspberries and blueberries. I also include blackberries regularly and when I can get them, gooseberries. But in small quantities, e.g. less than 100 gram portions a day, I've found that I can also eat other low sugar fruits occasionally - red and black currants, greengages, single apricots and little flat(!) peaches, figs, kiwi fruit, very small, or a few slices of apples, 2-3 orange segments, and a little rhubarb, without any significant spikes in my glucose levels. All of which I will eat with thick, double, clotted, or soured cream, creme fraiche, or full fat yoghurt, as part of a complete meal.
If your mother is using a meter, she will be able to test how such fruits might affect her glucose levels, and choose appropriately.
My LCHF diet was what reduced my HbA1c from an initial 60-61 on diagnosis right down to 40 eight months later. And kept it hovering at the lower end of of pre-diabetic levels for nearly three years now.
Robbity