If she does as little with windows as it sounds don't do anything fancy. Give her shortcuts on the desktop or in the favs and enable her to use her PC for what she does without distraction. Introduce the laptop parallel to her old laptop and let her try it first. If she doesn't like it you can dual boot windows or just install her windows. Don't try to hard making it like windows try making it easy to use.
If you go the windows route don't forget "open shell" and "o&o shutup" are essentials for a minimal migration from win7 to win10. Powertoys are nice as well.