Are you looking for something for her to use for defense or something for her to learn to shoot with? If its to learn to shoot with starting with a rifle will make her a much better shot, but you have to really focus on the fundamentals of marksmanship. Practicing with a .22 rifle in the prone and working on the fundamentals would be much better then practicing shooting a shotgun and letting the spread do the work. Then if she can shoot a .22 rifle with good form, she'll easily pick up a shotgun and she'll even have an easier time learning to shoot a pistol.