Chapter 16 of Little Women begins with the girls eating breakfast early to see Marmee off, and eventually having to watch her go, alongside Laurie, his father, and Mr Brooks.
It is basically how Marmee leaves to go see Father in the hospital after he had fallen ill. The girls are sad but they promised not to cry or anything, so after Marmee left they tried to keep themselves busy despite missing their mother. The rest of the chapter is their letters to her, plus Laurie's and others.
Chapter 17 begins with Beth asking someone to go visit the Hummels' since Marmee had told them not to abandon them, and only Beth had been going. Everyone said no, though, so Beth just laid down, but later she went out to see the Hummels.
Later, Jo found her crying in the medicine closet and Beth said the baby died in her arms from scarlet fever, and that the doctor told her to take belladonna immediately before She got the scarlet fever.
They decided to send Amy away to Aunt March just in case so that she doesnt get sick too, and Amy was mad at first and didn't want to, until Laurie promised to take her out all the time. Then later Dr Bangs arrived, and told them that Beth has some symptoms of scarlet fever, so Jo and Laurie went with Amy to Aunt March.