Walkthrough for Paternal Pride of Red Dead Redemption: Undead Nightmare.
1. Go to the green question mark in the MacFarlane's Ranch.
2. Clear the town from any zombies and meet Bonnie in his house marked with green question mark.
3. Go to the barn in front of you to find Bonnie's father.
4. Kill the zombies inside the barn and look for Bonnie's father.
5. Do what the game asks you and go back to Bonnie to tell her what happened.