What could be a possible essay question on these documents all together?
Actually, there are several ways you can look at this: one question could be "According to the documents, who would you blame for the Cold War--the West or the Soviet Union?" Another question could be, "How did each side justify its actions in the beginning of the Cold War?" Still another question could be, "How did America and the Soviet Union see its responsibilities in maintaining a new world order after WWII?" Yet another fine question could be "Given the rhetoric in Britain, the Soviet Union and America, do you think the Cold War could have been avoided?" although this question might require more external knowledge than you get from the primary source documents.
The Cold War is a fascinating study as historians over the years have come out as saying that it was primarily caused by the Soviet Union, primarily by the West, and primarily by the developing world who played one side against the other in return for maximum gains for their own independence movements. While your instructor may not use my questions, I have used questions exactly like those on tests about the Cold War era.