Never, ever, under any circumstances 'talk down' to a woman. Even if she's 4' 10".
Don't expect her to grasp the mechanics of riding immediately because women's brains work different than men's, (not inferior, just different) but she'll get it eventually. In the interim, encouragement is the keyword. Oh, and comfort. A soft seat and low enough to reach the ground with both feet.
A step through frame is an option too. There have been several very successful step throughs built. See Silver Bear's.
Tom