I can't really give you a step-by-step guide, but here's the gist of how I did it: I have a dexcom CGM, and use the dexcom share functionality in the app to sync the CGM data to a Home Assistant plug in. From there, the blood glucose data is treated like any other sensor value in Home Assistant, so the sky is the limit.

How you could implement this for your mom would depend on what brand of CGM she can get, and the level of tech aversion or savvy she is. xDrip and Nightscout are excellent projects which would also help you make something that uses or displays CGM data, if you didn't want to use Home Assistant.