It's had a few different titles, 'House by the Beach', 'Last House by the Beach', 'Terror', 'The Seventh Woman'... So all are valid.
The only actual release titles on home video as far as I know though have been under the titles 'Terror' (Cinehollywood VHS in Greece and the UK) and La Settima Donna (Italian VHS and Japanese & Sazuma DVD).
The Sazuma DVD is superb, a must have for fans of Italian exploitation cinema. Great bonus CD in that package too!