This is a compound sentence, because it has two independent clauses: 1. Melanie is going + but (conjunction) + 2. Valerie is staying home.
I believe the correct answer is to help the reader visualize a view where water and sky are difficult to tell apart.
The author is trying to portray an image where the water and the sky are somehow blending into each other - you can't tell where one ends and the other one begins, because both items are colored similarly - various shades of blue.
The phrases in this excerpt that help to reveal the meaning of the word "blight" are:
The meaning of the term Blight is <em>scourge, whiter, disaste</em>r.
The support of the meaning in the excerpt is "the last bitter hour": the final moments when someone is going to die.
“stern agony, and shroud, and pall": the end of a life using dramatical terms.
"breathless darkness": a kind of disaster that is coming, not to be avoided that paralyzed people.
