Oh, missed where you said SLUG gun. I would look at a 20 guage H&R ultra.
http://www.hr1871.com/firearms/index.php?cat=3&subcat=17
http://www.walmart.com/catalog/product.do?product_id=3138404
I own the Ultra deluxe in 12 gauge and like it. I have several posts about it on here.
She doesn't need a 12 gauge slug gun, 20 will work fine, and from what I read it might even be a bit more accurate. These guns are bit heavy, but handle recoil very well. Perfect rifle for her. Unless you are doign drives or a lot of walking.
Paul