It is possible that you will receive answers from my other colleagues too. Hitler's grandmother was not Jewish. There are some rumors hinting that Hitler's grandfather was Jewish. Few, if any, of the reputable historians on the Holocaust believe that this is so. It is more likely that Hitler tried to keep the murky history of his family quite secret because there was a high incidence of insanity and feeble-mindedness in his ancestors.
Rumors die hard, though.
One of Hitler's henchmen, Hans Frank, declared during the Nuremberg Trials in 1945-46, that Hitler's grandmother had worked in the town of Graz as a servant in the home of a Jewish family named Frankenberger. He further claimed that she was seduced by the head of the household and that Hitler's grandfather was the result of that liaison. A subsequent analysis of Frank's statement by Simon Wiesenthal disclosed that there was no evidence of any Jewish family named Frankenberger ever living in Graz. What is more, Jews had been driven out of Graz in the 15th century and had not been allowed to return until 1856, nearly twenty years after Hitler's grandfather had been born. Hitler's grandmother's maiden name was Schickelgruber.