Remark
This is a perfect example of the kind of question that works much better as an essay. You could pick AD or E and justify all of them along with mystery if it was offered as a sixth choice. If you have notes, perhaps that is where you should look for an answer.
The last line of the poem makes a pretty good case for a new "mythology." However I don't think it is the best choice. A is probably not right.
B: There is no trace of superstition. You can't pick that. Mythology is not superstition and belief in more than one deity is not superstition either. I don't think this is a reasonable choice.
C: I don't have any idea where equality comes from
D: I don't think this is about dreams so much as how they are delivered and by whom. Most of the poem is taken up by what Sybil is like and how she currently speaks. The last lines are about how she delivers what she has to say. I don't think it is really about dreams. It is about language.
I think it's E but any other answer (except C) would not surprise me. C would be a huge surprise.