I like this! ok....

1.) Probably... he'd look at the heirloom, look at the family, think and remember that if it was an heirloom of his own family's and some stranger found it, they would K.O.S. Since they are poor after all he'd feel less bad about giving it back and take the gratitude with a bit of regret doing so.

2.) Blankly stare, complain that this situation WOULD happen to him, and attempt to pacify the kids. If he's unable to quick enough or at all, run immediately in the opposite direction and pretend the scenario never happened.

3.) Fury spell on drunkard, invisibility spell on self, hide behind something and watch. All the while doing this in revenge.
[img=http://i1.kym-cdn.com/photos/images/original/000/359/856/4d9.gif]

4.) Attempt to get more of a reward from the guard. After all what if the beggar only has chump change on him?