The climax in the plot of a story is the most exciting moment where the reader is kept in suspense about how the story is going to turn out and the main conflict of the story is going to be resolved. In this excellent and powerful short story, the conflict is external, as Sade battles to do whatever she can to be reunited with her father and to try and live a life that is worthy of him and his ideals in the meantime as she and her brother adapt to life in England, which is very different from her life back home in Africa. The climax of this novel therefore comes in Chapter 41, when Sade is waiting to find out whether her father can be released or not. Note how this climax is described:
All they needed now was for Papa to be well again and to be allowed to stay with them. Was that too much to ask for? Mama had always said nothing was too much or too little to pray for. But Mama had believed in miracles.
Note the way that the doubt inserted into the final sentence adds to the tension as the reader is forced to wait with Sade to find out what will happen to her father. The rhetorical question clearly appeals to the reader to support Sade's argument of why her father should be released, yet it also promotes uncertainty as to whether or not he will be granted his freedom and safety. This is the climax of the novel, therefore, as the main conflict of the story is on the verge of being resolved one way or the other.
Thank you for your thorough answer, accessteacher!