Assume this is MK2 Golf we're talking? If so 88 onwards 16v has 256mm brakes, bearing carrier assembly will fit but you'll also need to fit the discs, pads, calipers & carriers, plus do both sides obviously

pre-88 16v has same bearing carrier assembly as your car so direct swap. ball joints on all MK2s changed size in 87, but best to double check what you have as you never know some pleb may have fitted the wrong bits to your car in the past. you could just press out the hub and press in another with a new wheel bearing.
many MK3 4 stud cars have the same hubs as yours as well, check the size of the brakes. if 239 direct swap, 256+ need to fit the discs, pads, calipers n carriers as well.