I had issues with my own printer (using it via WiFi), of going offline between uses (which might be weeks).
I can't remember how I solved it or what was causing it, but I was able to fix it. I think I gave the printer a static IP address. So start there if she's using it with WiFi. It was something I did, although I can't remember if it was that exact tweak that solved my issue. I do remember it wasn't a printer driver issue: that is, I had the most current printer drivers installed every time the issue cropped up. -I was pretty sure it started after a Sept/Oct cumulative update from Windows 10.