The chapter that contains the events you are refering to is Chapter Eleven, where Chielo, in her role as priestess, informs Enzima's family that the Oracle wishes to see her. Chielo therefore carries Enzima on her back as she visits the nine villages and then finally takes her into the Oracle's cave while Ekwefi waits outside. Ekwefi begins to fear for her daughter at this stage, because it appears that Chielo and her daughter, Enzima, disappear into a cave and are apparently swallowed up:
And so when the priestess with Enzima on her back disappeared through a hole hardly big enough to pass a hen, Ekwefi broke into a run as though to stop them. As she stood gazing at the circular darkness which had swallowed them, tears gushed from her eyes, and she swore within her that if she heard Enzima cry she would rush to defend her against all the gods in the world. She would die with her.
This chapter does not actually tell us what happens to Enzima when she is taken to the Oracle. The event is appropriately shrouded in mystery as befits such a revered personage as the Oracle. The next thing Ekwefi realises is that her husband comes to relieve her and so she goes home to bed while he awaits Enzima.