Answer:
b. The characters are more apt to act in the daylight, and they feel a sense of relief.
Step-by-step explanation:
While I have not read the entire passage and do not know the context of this line, I do know that when it says "awakening from a nightmare" it is implying that the characters are no longer incapacitated and scared. By saying that the "paralyzing atmosphere of fear" was gone, it implies that the characters are no longer paralyzed or stuck in one position and unable to do anything. Now that they are no longer stuck, they can act freely how they wish, which lines up nicely with answer B.
Hope this helps!