Of the possibilities you list in your question, "confusion" is probably your best bet when comparing "Prufrock" and "The Second Coming."
Prufrock suffers from confusion typical in the modern world. He doesn't know if making the attempt at a relationship would be worth it, in the end. With his allusion to Hamlet's "To be or not to be" speech, Prufrock connects himself with the inability to make a decision. The allusion also connects him to the question of whether or not existence, as a whole, is worth the effort. Prufrock struggles with how he appears to others and what others will say about him. He speculates on what will happen when he arrives at his destination, and then never actually arrives. Prufrock isn't sure if he should go, if he really wants to go, or what will happen if he does go. Prufrock is confused, most specifically, on a personal level, although the confusion extends to existence as a whole in the modern world.
"The Second Coming" deals with confusion on a grand scale. The falconer's inability to communicate with his falcon is a direct reference to confusion. The massive destruction and cruelty of the Russian revolution is also referenced, as may be WWI. The "bad" are enthused, and the "good" lack intensity. The world is a world of confusion.
Yeats believed some pivotal event occurs in human history every 2,000 years. Viewing the birth of Christ as one such event, the poem is about whatever will come next. Whatever is in store for humanity, though, the rough beast will be coming into a world of confusion.