There are two parts to the quest. The Mafia Wars Quest I requires you to clear three Skulls, clobber three Snakes, and chop down three trees. To spawn skulls, you should clear a small area in your homestead. Clearing Skulls have a high chance of getting Snakes. That should take care of those requirements. Chopping down trees should be easy.
The Mafia Wars Quest II is nothing but a popup that announces that you’ve earned the Bowie Knife in Mafia Wars. Now you can check your newly acquired weapon in your Mafia Wars inventory.
If you haven’t started the Mafia Wars Quest in Frontierville, you can click on this link: http://zyn.ga/1AQ
This is an easy cross promotion between the two popular Zynga games. Frontierville players are looking for new goals and they got it. Plus, it would also benefit players who also play Mafia Wars.