Shelf life for any hop style (leaf, pellet, plug) depends on the type of storage and packaging. Nitrogen-flushed or vacuum-sealed packaging is your best option, and ideally they would be frozen. If they were stored at room temp they will have lost some of their bittering potential, and they can even get kind of cheese-y smelling if stored incorrectly for a long time.
If it were me, I'd buy new hops since it's probably only a few dollars worth. That assumes you know what kind they are. I'd guess they were Kent Goldings.
If your kit contained liquid malt extract, it can degrade over time as well, getting darker and maybe picking up some oxidized flavors. I've read that it's best to try to use fresh liquid extract whenever possible.
You could also just go ahead and make it and enjoy it for what it is - it will still be beer, and most likely pretty good beer.
Fermenter 1: Best bitter (1)
Fermenter 2: Best bitter (2)
Fermenter 3: APA
Fermenter 4: APA