In the context of The Crucible, Sarah Good's exclamation about "His Majesty" could be interpreted in a few ways. However, in this case, the most relevant interpretation is B. She's about to be hanged.
In Act 4, the characters face the consequences of the witch trials, and Sarah Good's mention of "His Majesty" may reflect her desperation and confusion as she confronts her impending death. It could also suggest a moment of dark irony where she equates the authority and judgement of the court with a higher power, as she is being led to execution.