Puzzlement is the correct answer
Gregor can't handle the furniture moving. He crawls out from behind the couch and globs onto the first thing he sees. It is a picture on the wall of a woman in furs. I think Gregor doesn't want to lose the possibility that he might become human again. The furniture reminds him of this.
With quotes, and things like that but the quotes work the best and the teachers love that stuff, they just seem to eat it up.
Here are a few universal themes conveyed in this scene.
The battle of good and evil. Beowulf is a young warrior who wants to stop the terror of monsters. He is a paragon of good, just like Grendel's mother is a paragon of evil. She is an implacable force of evil, who tries to exterminate the hero who has dared challenge her.
Courage and self-sacrifice. Beowulf has many reasons to fear the furious monster who wants to avenge her son's death. Nevertheless, he enters the battle, fully aware that he is risking his life. His courage is one of his heroic traits, which separate him from other humans.
Magic and supernatural. First, there's the fact that Grendel's mother is living in a lake. Then, there's the ancient sword that seems to be the only way to kill this monster, even though it melts down after Beowulf has decapitated Grendel's corpse with it. Then, there's the fact that Beowulf somehow manages to survive under water, even though he is only a human.
