Fallout 3/Trouble on the Homefront

This quest is available soon after The Waters of Life, and is obtained when you hear the Vault 101 Emergency Signal; you will notice the signal when you are near Megaton.

Vault 101
After re-entering the Vault, you'll have a small chat with Officer Gomez, who states that after you left, a problem occurred within the vault; in particular, some members wanted the vault to be opened permanently, and the overseer strongly disagreed with this.

Talking to the Overseer
You can speak to the overseer to convince him to step down as the vault leader. In doing so, you will receive a modified utility jumpsuit that increases your luck, repair skill and radiation resistance.

Assassinating the overseer
You can kill the overseer.

Sabotaging the vault
You can sabotage the air filtration system within the vault in order to force everyone to leave. This requires a Science skill of 75.