Yes, they're all correct.
As a native speaker of English, I'd say that all of these sentences are correct and meaningful. There is some slight differences in meaning, largely due to the differences in tense, however.
I would say that B would mean that anyone who has not done their homework by tonight will not be allowed to watch television, while C would mean that anyone who has not already done their homework (as this sentence is said) will not be allowed to watch television tonight. Sentence A is somewhat more ambiguous about timing, but it's saying that watching television will not be possible without the completion of homework; it's a somewhat stronger way of saying "will not be allowed".