During an early morning fire on East 93rd Street between 2nd and 3rd Avenues yesterday, an elderly wheelchair-bound woman and her son died. The victims, 89-year-old Anna Roberts and 65-year-old retired postal worker William Roberts, were longtime residents in an rent-controlled unit; a neighbor, who escaped by going to the roof and climbing to another building's roof, told the Post, "I had a hard time getting out, so I could imagine they had a real......