What about an Option 4 (that would require baseline intelligence writers that have an understanding of the lore): The Vault-tec experiment for 33 was to gauge the reaction to the ghoulification of some of the Vault dwellers. Watching your friends and family turn inhuman with the potential of feral ghouls could be interesting if done well.

Or Option 5: With the knowledge that becoming a ghoul brings grim benefits, some of the dwellers would willingly choose to become ghouls to help stretch supplies and/or save themselves from an uncontrollable radiation issue.

More likely one of your options though. A damn shame.