The mysterious disappearance of “Today” show host Savannah Guthrie’s mother is being investigated as a crime, authorities said Monday — citing “suspicious” circumstances at the 84-year-old woman’s home.Nancy Guthrie was last seen around 9:45 p.m. Saturday at her million-dollar residence in the Catalina Foothills area near Tucson, where officials found a “very concerning” scene, Pima County Sheriff Chris Nanos said at a press conference.“We know she didn’t just walk out of there. She did not leave on her own,” Nanos said. She is very limited in her mobility,” he said — explaining the grandma “could not walk 50 yards on...