How does the fourth ode set the mood of the
scene and how does it contribute to the
themes of the story?

Based on the speaker’s allusions in Midsummer to Shakespeare and sonnets, readers can infer that the speaker is deeply familiar with Shakespeare and his works.

Explanation:

Derek Walcott's "Midsummer" is a collection of poems that he wrote, one for each year of his life. This book contains the author's own confusion at his Caribbean colonial to the culture of Europe and its literary traditions.

One poem is titled "XXIII" where he mentions "Shakespeare", "Sonnets", "Caliban", "Moor" etc. all parts of William Shakespeare's literary works. This allusion to the famed writer's works shows that Walcott is deeply familiar with the works of Shakespeare.

Thus, the correct answer is the third option.