The conclusion will depend to a great extent on the nature of your essay and, if it is argumentative, what your argument has been. Nonetheless, many of the best conclusions take the principal ideas of the essay in a new direction or apply them in a new way, so there are some conclusions which would fit a variety of essays. Several of these would consider the future of Antigua and its people.
Kincaid describes the slave owners as "human rubbish from Europe" and the slaves as "noble and exalted human beings from Africa." However, though she is suspicious of the descendants of slave owners and has solidarity with the descendants of slaves, she says that these categories no longer apply. The black people and white people now are "just human beings."
You might use the conclusion to consider whether this is a convincing peroration and whether it is supported by the rest of A Small Place. Elsewhere in the book, Kincaid does not seem to believe that the legacy of slavery can ever be erased and regards the modern-day tourists as exploiting the island and its people in a manner consistent with, if less horrific than, the depredations of their ancestors. What future do you see for Antigua? Can it involve tourism? Is there a non-exploitative way for outsiders to experience the island? Does Kincaid provide answers (perhaps conflicting answers) to these questions?