I would love to help but I’m afraid that there’s a book that is behind this and I haven’t read it so I wouldn’t know how to answer these questions.
I believe that MLK's dream has not completely come true in present day America. He states that "my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character". However, in recent news there was a rise of police brutality that is completely on the basis of discrimination. In order for his dream to come true, there should be no possibility of anyone, or his children, being treated differently due to skin color. I am not entirely sure if this discrimination applies to all social classes, but I know that we still have work to do in obtaining this dream.
Vanquished means to be conquered or defeated, so it is B. You could say the ememy has been vanquished or conquered.