The quote highlighted in this question occurs in Chapter Six and is part of a conversation that Ekwefi has with Chielo, who is also the priestess of Agbala, the Oracle of the Hills and the Caves. They are talking about Ezinma, and in particular note the following exchange that they have about Ekwefi's daughter:
"She hs been very well for some time now. Perhaps she has come to stay."
"I think she has. How old is she now?"
"She is about ten years old."
"I think she will stay. They usually stay if they do not die before the age of six."
Ekwefi was considered to have born a spirit child in the form of Ezinma. This is shown in the number of children she had born before who died in their infancy. Ibo culture believed that such spirit children were born in the form of humans but so desired to return to their original state that they would die quickly afterwards. This conversation, and Ekwefi's statement of hope that is quoted in the question, indicates the way that the Ibo believed life was a matter of fate and the result of supernatural influence rather than of free will. Ekwefi is only able to "pray" for her daughter's safety and long life, and thus it is revealed that the Ibo have a radical belief in supernatural forces that they believed controlled their lives.