The Grapes of Wrath was a story of false hopes, thwarted desires, and broken dreams. Explain.How can we answer this question in a form of an essay?

To add to the great ideas of the first answerer, I thought
I would further expand upon your question of "how" to answer in the form of an essay. 
Quite honestly, your professor did a great job making it easy for you to write a
five-paragraph essay in a definite form!  The original question is a perfect thesis
statement.  I would begin the introduction with a current example of a book/film that
shares similar themes.  Of course, end your introduction with the thesis.  The three
body paragraphs are nicely indicated there:  one for false hopes, one for thwarted
desires, one for broken dreams.  Using The Grapes of Wrath it
should be very easy to find three examples of each.  Finally, in the conclusion
(after you reword your thesis), I would focus on the possibility of hope, especially
through the very moving image that ends the novel, . . . one that possibly turns a very
tragic situation in to one with hope for the future.