The correct answer is B. Aunt Martha has both a kind and cruel personality.
Step-by-step explanation
In writing, an allusion occurs when the author of a text makes reference to an external idea such as a place, person, even or even a literary work, idea that in most cases is not explicitly explained but that is linked to the ideas presented in the text. In the case of the passage, the author states "They couldn't predict when she would turn from Jekyll to Hyde" which is a reference or allusion to the main characters in the novel "Strange Case of Dr. Jekyll and Mr. Hyde" in which Dr. Jekyll is a scientist that finds a way to turn himself into a different person which is opposite as Jekyll is friendly and king and Mr. Hyde is evil and cruel, this means the author refers to Aunt Martha as someone unpredictable or that can turn from friendly to evil in the way Jekyll turns when he becomes Mr. Hyde. This is explained in subsequent sentences as the author states Aunt Martha was mainly kind to Tim, but one day he grabbed him by the shoulders and shout at him and then went back to the had a kind attitude again. Therefore, the allusion in this passage means "Aunt Martha has both a kind and cruel personality".