The answer to this totally depends on how long, since when, and to what extent has the person been blind.
If a person has been blind since birth, they’d just have auditory dreams, i.e. all dark, with just voices. but if a person used to be able to see, but lost his sight later, they’d dream just like normal people do i.e. in color, or perhaps, as they get used to being blind, their dreams might reduce to auditory ones, and if they arent completely blind, but cannot exactly dream very well either, and have been this way for a long time, their dreams too would be all blurry and obscure, just like their vision.
I never exactly met a blind person to ask, but well, after researching a bit, and well, applying a bit of common-sense, stated above is what i believe.