Evidence for how Tilly and Delphine and Colinda left to find Noah.

From the text:

I didn't doubt but that Noah was sick. He'd have the trots by now, the way they were eating. We'd heard about the pneumonia the boys had brought with them from the
wet ground they'd slept oh at Jacksonville. We knew about the measles, and there was typhoid talk. Dr. Hutchings had said Cairo was a pesthole. But how could I go? I didn't knowwhere the world was, how to get there. Gray light streaked the window.

Calinda sat across the table from me, hung in shawls, warming her long hands on
the mug. "Me, I stay at 'orne," she said a moment before I asked her to go with me. "I see to things here." Calinda was such a miser with her words that you believed every one of them. Still, I had to say, "But they's sickness down there, and you know the cures." Did it dawn on me that I was asking her to help her enemies, if that's
what our side was to her?
Her arms were folded now, and her face seemed darker in the brightening day. "I send the cures with you, you and Delphine."
Delphine? What earthly good would-
"If you go among men," Calinda said, "she come in handy. She is meant for men." And Calinda said no more.