Decapitated Granny in Wheelchair on Lift in '60s Film

by Swan
(Chicago, Illinois, USA)

What is tittle of 1960s horror movie involving a child raised as the opposite sex who grows up to murder the mother or grandmother responsible for rearing him/her?

The clock on the screen gives the audience 1 minute to leave theater before scene in which the invalid descends stairs in a wheelchair via a stair lift. When the lift comes to rest at bottom of stairs, her head rolls off. She has been decapitated.

Thanks.