In the end, you know your students, your time constraints, and the manner of assessment you have used all year. The answers you get to this question will have to be tempered within this, so take what you get here with much in way of modification in terms of what a final would resemble. I like the critical lens question as I think it gets much in the way of Steinbeck's message in the work. I think that you can explore this question in a variety of ways for students to demonstrate comprehension of the novella as well as developing reflective thought regarding the critical lens question. I would start off with 10 multiple choice questions that center on events or ideas from the story that deal with great love, great achievement, and great risk. For example, "Who shot Candy's dog?" would be a good question that talks about the love present between Candy and his dog as well as the risk involved in having to stand up for that which one loves. I would progress into a small writing section in which students are given the critical lens question and then have to identify how two characters represent this idea. This would be no more than three to four sentences each that explain who the character is in terms of what they did in the story and how they represent the critical lens question. Finally, I would feature a bit of longer writing prompts that ask students to examine the presence of the critical lens question in a larger sense in the novel. For example, how is the question represented in the novel with specific characters and action. I would also delve into the question as to how the ending of the novel validates or repudiates it. These avenues could be worthy of pursuit in the composition of a final based off of the critical lens question offered.