I have a grown daughter in that looks like she might be in that situation soon herself. She's 90 lbs soaking wet so she's kind of limited in terms of recoil absorption hand gun or long gun.
We've pretty much settled on a youth model .410 pump loaded with buckshot. Manageable recoil, easier to hit with than a handgun and hits harder than any handgun she can manage the recoil on.
Just had an idle thought. Do you think they make a bayonet mount that could be adapted to a .410 barrel?