Final answer:
The narrator gets lost as he explores the dungeon, stumbling upon a hidden society with hostile residents after seeking solitude.
Step-by-step explanation:
As the narrator explores the dungeon, he does not find an exit, encounter a monster, or discover hidden treasure; instead, he gets lost. In the passage provided, the narrator, feeling estranged from the laws of men, seeks solitude and inadvertently stumbles upon a hidden society after going through a huge stone door.
He is confronted by the residents with apparent ill intent, asking for his identity and accusing him of trespassing. This scenario is more akin to the narrator getting lost in a new and unexpected place, rather than any of the other options provided.