Aw, that's a very difficult situation!
but its really hard getting my mum, who struggles with memory to focus and understand the new systems, insulin and how she has to change.
A basal/bolus system, with mealtime insulin before every meal might prove too complicated for her to manage herself with memory and focus issues.
I can imagine a high risk of double dosing before meals or forgetting doses, and focus issues may increase the risk of taking the wrong dose as well.
Does she have a nice diabetes nurse who's willing to spend some time trying to help you and your mum to find a way which can work for her?
Until some time ago, many people were on a mixed insulin regime, usually taken twice a day.
This system isn't flexible at all, you need to eat at fixed times, and have meals with approximately the same amount of carbs every day.
So thankfully for most of us, this has changed to basal to keep us steady without food, and bolus to take before eating at whatever time we like, adjusting the doses depending on the carbs in our meals. This gives us much more freedom of course. For most, it's possible to keep diabetes much more stable on this dynamic system, because we can adjust and readjust countless times a day.
Now for your mum, this may be different.
If she doesn't mind a regular life with regular meal and snack times, taking a fixed dose twice a day is much easier to remember that juggling two pens with different insulins and different doses at different times of the day.
This might be worth considering with her diabetes nurse.
Please don't hesitate to ask anything, both on the forum and with her diabetes nurse!
Good luck!