4 year old DME?- no problem
4 year old LME? As Rob mentioned above, it'll be darker than fresh, and depending on how it was stored, could be oxidized and stale.
4 year old hops, in original nitrogen-purged packages? if stored in a freezer, no problem. If stored at room temp, then there might be some degradation.
4 year old yeast? Get new. Even if it is dry. A package or 2 of US-05 is cheap insurance.
Me- it was a free kit of something I've haven't done before(and is an expensive kit), so I would brew it, and take my chances.
Good luck, and let us know!
By the way snix- Welcome to the forum!