"'Stranger,' he grumbled back from his brutal heart, 'you must be a fool, stranger, or come from nowhere, telling me to fear the gods or avoid...

A. Monsters are stronger than the Greek gods.

In this particular passage, it seems as though option A is the best answer.  Polyphemus, the Cyclops, believes himself to be stronger than even the most powerful of the Olympian gods.  Though he turns out to be wrong, Polyphemus, son of Poseidon, continues to believe that his race has the superior power.  Odysseus has referenced Zeus and Zeus's protection of travelers because Odysseus would expect to be treated with great hospitality. The ancient Greeks felt that there was, thus, a religious imperative to offer a hearty welcome, with food and lodging and even gifts, if the host could manage it (and Polyphemus certainly can).  Therefore, option A seems to best describe Polyphemus's feelings about his relative power compared to the gods.  However, elsewhere in the text and in Greek life, while monsters could do a great deal of damage, they were not believed to be stronger than the immortal gods.