I read this in Harry Potter Wiki; "It is unknown which house she was sorted into. However, it is possible that she was sorted into Slytherin, due to her prejudice against Muggle-borns and half-breeds and her Inquisitorial Squad consisting of only Slytherin students." It seems reasonable,doesn't it?
Yeah she is definitely too mean for Hufflepuff and she was dumb enough to believe in @dumbledores secret weapon so she's c ertainly not Ravenclaw and personally I doubt she's a Gryffindor so that only leaves Slytherin
