when she is finally reunited with her father how does he disappoint her

As they walk out of the CENTRAL Central Intelligence building, Meg feels despair. She had thought that by finding her father everything would turn out okay, but she now realizes she was mistaken. She wants to give up, but Calvin urges her to continue forward. They walk down a street and come to a domed building - the place where IT is housed. As they enter the building, Meg discovers exactly what IT is...a “dismembered brain.” Meg thinks that it is the most horrible and disgusting thing that she had ever seen.

Meg was disappointed when she was reunited with her father because she had expected everything to suddenly work out, and go back to normal. She was disappointed when she realized she would have to work a little harder to get her normal life back.