The pronoun I
is obviously a reference to Nehemiah himself. Accompanying him were a few men.
The word few
indicates the smallness of the group, conceivably no more than half a dozen men. Presumably, these are trusted locals who can show Nehemiah the extent of the damage to the wall, specifically what he cannot see from within the city.
12 Then I arose in the night, I and a few men with me. And I told no one what my God had put into my heart to do for Jerusalem. There was no animal with me but the one on which I rode.