Cody subconsciously knew the Canker Man was his mother.
- That would explain why it went after school bully Tate. Cody might not be familiar with the Mama Bear trope, but the Canker Man showed up right when Tate was closing in on his sleeping victim, and called up somebody to protect him. Who does an eight-year-old boy instinctively turn to for protection? Mom.
Cody is a fledgling Reality Warper.
- This is suggested not only by his dream manifestations but also the ending scene where he is able to manifest a butterfly while awake. While this could be cool, a small boy only stays innocent for so long, and he will require careful guidance from Jessie to remain well-adjusted (especially in light of his past) and not be tempted to abuse his abilities as he grows more powerful.