Notice a pattern here? .22 is perfect for first time shooter. No recoil. Accurate. Cheap to shoot.
Also advice about taking her to the range when it's not crowded is right on, particularly if it's an indoor range.
When I first started shooting I went to an indoor range where the guy next to you might be shooting a .22 pistol, or a 300 Win Mag with a muzzle brake. Even with hearing protection it is very hard to concentrate with that much noise next to you. For a first timer, who's already a little nervous its impossible.