If they're T90 pellets, they've remained in the freezer, and they're in the original Mylar, nitrogen-flushed packaging, they'll probably be okay.
If they're plugs or whole flowers, the only way to really tell if they're good is to open a package or two and evaluate them. Squeeze 'em, smell 'em, feel 'em, look at 'em.
Do they smell good? Nice and "hoppy"? Pungent? Rancid? Stinky? No aroma at all?
Do they feel good, springy to the touch, not dry and papery?
When you open a compressed flower, can you see the yellow/gold lupulin at the base of the bracteoles (petals)? Is it yellow or darker, more like orange?
When you take a flower or two and rub it between your palms (think Jim Koch in those Sam Adams TV adverts about hops), do your hands smell good? Are they sticky with hops oils?
If they're plugs or whole flowers, they might
be okay for use in flavor/aroma applications, depending on the outcome of the sensory evaluations described above. Alpha acid degradation has probably reducing the bittering potential to nil
At the very least, you can sell them to Belgian-ale brewers as "perfectly aged Lambic and Oud Bruin hops"!