Do not hand her anything larger than a .22 unless she is completely comfortable with it.  Nothing turns off an anti faster than recoil and loud noise.  It reinforces the feeling of power, and power that could potentially be in someone elses hands is what they fear most.  I have taken many antis and far leftist types on thier first shoot.  Usually I start with a .22 pistol and a .22 rifle.  I often use an Ar with a rimfire kit.  Once they realize that it is the same iddy biddy .22 that they may have seen or shot in daycamp and I explain that this is the cartridge that most children learn to shoot at the YMCA camps they become comfortable.  When they are ready I switch upper and put in a .223 with 5 rounds.  I explain that this is the setup that is often used to get rid of groundhogs as well as in National and international shooting sports competition.  Most comment on how fun it is.  In the end of course I let them know that its also the favored caliber of the police and military, largely because it is easy to shoot and not as powerful as those evil deer hunting rifles.  Good luck and do not overwhelm.

Start with a .22 for sure, I find my 22 kit for my AR is great for this.

Reactive targets are the best thing for new shooters. Balloons, cinder blocks, and my favorite the old fire extinguisher hung on para cord (you can hit it with .22 for ever and it will make a nice sound and still hold up).