In your/her situation, I'd go for a hardtail MTB.
MTBs are fine for tours, especially short tours like the length you mentioned. Use slicks most of the time, and hang onto the MTB tires when needed. This also gives you the option to do off-road tours, if you are so inclined.
There are lots of hybrids out there, but I'm not sure how good they are for the off-road riding.