Then I guess he must abandoned her there in the dungeon, to be eaten by monsters. No other choice, since he can't possibly save her. People would be suspicious of a middle-aged man saving a young woman, after all. How scandalous! Absolutely better just to let her die.
I see the author's penchant for irrelevant gag manga jokes is still going strong. I hope the author managed to convince an editor that his true calling is gag manga, not adventure.