Cannondale road frames tend to have longer top tube than some. I agree that if it fits and she has reasonable skills it will be a fine bike for her. There is a lot of talk about 28mm or larger tires these days but 25mm will be fine for most people, especially for shorter rides and good pavement. I rode 23s for 30+ years on everything and only went to 25s last year. If it will fit 28s then try them if you like.

If you don't have a handlebar yet remember they come in different widths, reaches, and drops.