Answer to the First Question: Option D. The mother of the dead man.
The mother of the dead man is not a participant in the poem. She is not mentioned explicitly in any of the verses, and there is no evidence to prove she has an impact over the dead man current situation. It could be argued the mother plays a role in the line "'It must have been too cold for him his heart gave way'... They said", but this phrase is rather atributted to the dead man's firends, as the speaker of the phrase is refered as "They".
Answer to the Second Question: Option A. Detached.
"Detached" is described an adjective referring to the state of being separated or disconnected. The narrator should be considered to feel "separated" from the dead man, as it seems that the former knew the dead man a bit, and he no longer resides within the world of the living.