A homeless maniac stabbed a 75-year-old woman in the neck as she waited for an Uber in Brooklyn after the nutjob eerily grunted “hello” to her, cops and sources said Monday.
Shawnee Moore, 36, — who has three previous arrests on his record, including a bust for another random attack — greeted the victim as she waited for her ride at Glenmore and Christopher avenues in Brownsville around 11:25 a.m. Sunday, authorities and sources said.
Moore then hit the unsuspecting woman with a stick and stabbed her in the neck with a knife, cops said…