WENDY PIERRO Acorn Newspapers FESTIVE ACCESSORY- Volunteer Jessica Alexander is dressed for the occasion, wearing an elaborate mask. Saturday night marked the 17th annual Mardi Gras Ball. The event at Hyatt Westlake Plaza was a fundraiser for Community Conscience, the "one-stop human services center" in Thousand Oaks on Hillcrest Drive at Moorpark Road. The gala included silent and live auctions, dinner and dancing. The queen and king were Susan Holt and Harry Selvin. Fat Tuesday was earlier this week, and Lent began yesterday.