Your question indicates that you have either chosen or been given the paper's intended direction. Your essay needs to focus on how The Road to Mecca displays trust, love, and friendship between the characters. Fortunately, the character list is not large, so you are forced to closely examine Miss Helen, Marius, and Elsa.
My recommendation would be to focus on Elsa and Marius because their actions display trust, love, and friendship toward Miss Helen. There are moments when Miss Helen displays those traits toward the other characters, but the majority of those traits in action come from the other two people. Elsa and Miss Helen clearly have a friendship based on years of trust and interactions. Elsa fiercely defends Miss Helen's lifestyle, and she wouldn't do that if she didn't trust Miss Helen's ability to continue on her own and love her enough to defy the community's wishes.
Marius is similar. There are moments when it appears that Marius has feelings beyond pastor and congregant for Miss Helen:
“There is more light in you than in all your candles put together.”
You can pursue that angle, or you can pursue that Marius is representing a more traditional agape love of a church leader seeking out and trying to care for a member of his flock.
Regardless of which exact angles you want to pursue, you need to start with a thesis statement. The thesis will guide the essay and keep individual paragraphs on track. Always refer back to your thesis and consider whether or not a particular point ties back to the thesis. If it doesn't, then don't write about it. The thesis doesn't have to be complex.