Agreed. It was tempting to say "a light and a multitool". But... if you could only have one item... which would you choose? (In a city.)

Actually, it's probably not a qood question. For one thing, we don't have to limit ourselves. Second, there are reasonable scenarios (like yours) that would require two things (light and multitool) to solve.

Ok. Amend the bare minimum to "light and multitool". <img src="/images/graemlins/smile.gif" alt="" />

(This is ignoring, of course, the "hassle factor" from various security checkpoints about the multitool. Just carrying a flashlight is unlikely to attract any attention. The multi tool, blades or no, could be a problem in some situations. So while you might need a multitool, not carrying one gives you maximum freedom of movement. i'm not arguing against carrying one, just sayin'....)