The right answer is " B- Macduff is acknowledging that Macbeth is a traitor to the throne "
This is part of the scene where Macduff kills Macbeth and separates his head from his body. When Macduff speaks "where stands Thur usurper's cursèd head." He is referring to the head of Macbeth who was a traitor to the throne by assassinating the duncan king and taking the throne in his place. In addition, in this passage, Macduff is paying Malcon as the new king. And that explains which of the alternatives shown in the question is the correct one.
After Macbeth slays the young Siward, Macduff charges into the main castle and confronts Macbeth. Although Macbeth believes that he cannot be killed by any man born of a woman, he soon learns that Macduff was "from his mother's womb / Untimely ripped" — meaning that Macduff was born by cesarean section. The two fight, and Macduff slays Macbeth offstage. Macduff ultimately presents Macbeth's head to Malcolm, hailing him as king and calling on the other thanes to declare their allegiance with him .