The theme which the excerpt best supports is the following one:
B. It is important to be grateful.
The character is aware of how terrible his current situation is. However, things could be worse. After all, he didn't drown like the rest of the crew, whose lives ended and cannot in any way carry on. Even though the narrator is in a desolate place, "void of all hope of recovery", there might be a chance for him to find a way out, even if it takes years.