The Stone Isn't There

"I ..." Jon started, but then he remembered that he was supposed to be the "mother" of this family. So why not use that to his advantage? "What I'm doing is none of your business. Now go downstairs and wait for me with your sister." "Jeez, whatever, Jom," Susan said. "I was only asking." Then she turned and headed down the hall to the stairs. There was that name again - Jom. Perhaps it was a mix of Jon and Mom? But why bother? If he was supposed to be the "mother", why not just call him Mom? He shook his head, putting it behind him. After searching a few more places in the room and coming up empty, Jon realized that the stone was definitely not there. But if it wasn't there, then where was it?