IMO A.
What is the OA?
(A) herself an escaped slave, returned again and again to Maryland to guide
(B) being an escaped slave herself, returned again and again to Maryland so as to guide
-- "so as"-redundant
© an escaped slave herself, returned again and again to Maryland for guiding
-- will consider the advise "avoid statements with -ing form in it"
(D) herself as an escaped slave, returned again and again to Maryland so as to be the guide of
--"so as"-redundant
(E) who had been herself as an escaped slave, returned again and again to Maryland for the guiding of
--"for the guiding of" is wordy.