How is April's conflict resolved?

The main conflict in the story is the internal one that April has with herself over her mother. April struggles to accept that her mother, having left her, is never coming back. Not surprisingly, April feels abandoned and lacks the emotional maturity to make sense of what's happened to her. Until she can resolve this inner conflict and accept that her mother's never going to return, April will remain in a state of constant tension, unable to relate to the people around her or form meaningful relationships with them.
Thankfully, her experiences with her Grandma and the other kids in the Egypt Game gradually allow April to feel loved, wanted, and accepted again. April becomes so happy with her life that she's able to turn down an invitation from her mother to spend Christmas in Palm Springs. In doing so, she finally resolves the inner conflict that had tormented her for so long.