In my opinion, the whole poem is quite ironic - although she is mentioning the exultation and the royal color of death, the poem itself begins with the narrator saying that she cannot breathe - that she doesn't want to die.
So, I would say that the ironic parts are:
Exultation is the going
Of an inland soul to sea, -
Past the houses, past the headlands,
<span>Into deep eternity!</span>
Answer: the authors last name
Explanation:
In MLA format, works cited are typically last name, first name, title of work, publication date and page numbers