Ok my mind is going crazy; another theory here:
AB contacted police, told them of what happened, how he helped EB put a mattress in the Tahoe. Then he proceeds to tell the police he is going to the airport to meet his mother.
While EB was at the Airport, the police move in on a tip that EB gave them about the mattress. The tip rang true; so they dispatch to the airport and asked him to come to the station for further questioning. EB agreed, while there they read him his rights and placed him under arrest. His mother's flight was probably delayed or she got bumped off a flight. That is why he probably was at the airport at the time when no flights were scheduled because he was hoping she would be there in a few hours. He had no place to go so therefore he just stayed there.
After questioning AB more, they learn more information and this is when the goods pointed mostly to EB. Once they took her to the site and informed her attorney that AB has informed on EB, AB's attorney advised her to work with the police to find her.