(A) struggle, caused by economic inequity, bringing about the universal workers’ revolution that would end history -- Incorrect. Fragment. "Class struggle" the subject has no verb.
(B) struggle, due to economic inequity, would bring about the universal workers’ revolution, thereby ending history -- Correct. "class struggle" has a verb now "would bring". The present participle is modifying the preceding clause "class struggle would bring about UWR" and is correct. It is showing the result (effect) of something. Proper usage of present participle.
(C) struggle, which was brought about by economic inequity, causing the universal workers’ revolution that would end history -- same as A. Fragment.
(D) struggle was because of economic inequity, and it would bring about the universal workers’ revolution and the end of history -- Multiple errors. "was" isn't the appropriate tense when talking of a theory / principle. Simple present works better. Secondly, it is the revolution that would bring the end of history and not the class struggle. Sentence conveys that class struggle would bring about A (revolution) and B (end of history). This is incorrect.
(E) struggle was due to economic inequity, bringing about the universal workers’ revolution and ending history -- Same as D. Tense error and meaning error.