[GuinnessStout]

A lot depends on what level trails she is meaning, but for the basic entry level trails the dual bikes are good for both. Tires can be a pain, some people can handle fats on the road others can't BUT you will work a LOT harder to get moving on fats on the road, I actually ride fats on the road because I am too lazy to switch over my rims sets all the time and I refuse to buy another bike right now because I prefer to trail ride only.
But yes start easy... even riding as much as I did I still came out of a sharp curve hot a patch of roots so hard that my shoes came unclipped (I ride clipped into my pedals for power) went over the handlebars and cracked 2 ribs THEN still had to ride an hour back out of the woods.