The source is dated but still useful, B
B, as there is no point in a comma there. There is already an and in the sentence which is a conjunction.
because
Explanation:
I don't know man but ask a tutor forreal
I believe The dream is a warning, but also Grendel is saying that he and Hrothgar are connected. Grendel thinks that religion is pointless/meaningless and that it just follows a bunch motions.