First, as far as I know, Walmart's policy is to comply with local laws. In that case, you can carry concealed at that Walmart.
Second, carrying is a personal decision. You and your daughter will have to make that decision separately.
Third, even if she were carrying in the situation she described, her actions should be the same as those she took.
Fourth, a course in defensive pistol situations, beyond the usual CCW/CHL course might be a good idea. The 150 Course at Gunsite might work, but there are probably other shorter courses available in your area.
http://www.gunsite.com/main/course-o...ol/150-pistol/
The Scottsdale Gun Club has a number of courses, including "Ladies of Liberty." Check it out.
http://www.scottsdalegunclub.com/ind...d=27&Itemid=73