I believe so, the front takes 77mm filters, presumably to avoid vignetting. Remember that you'll get uneven skies with a polarizer on any wide lens because the polarization of the sky varies, at least on sunny days. I'm not sure about cloudy, I never thought to check.
As long as you have the insert for it you can use it on all lenses. But since you have it fitting the 80mm you must have the insert. Just remove it from the polarizer and it will fit on the 50mm lens. But I don't find a polarizer that useful on the wide angle lens because of unevenness in the sky.