The mountaineers are desperately short of food and medical supplies. Moreover, they are likely to be stranded for another week until the weather clears.
The correct answer is B. moreover.
These two sentences both show us something bad: not only are the mountaineers in need of food and medical supplies, but on top of that, they will be stranded for a week. A and C do not convey that both situations are horrible, but B does.
