Nan Waite collection

Nan Waite has forwarded a set of photos from a specific event, and two more of Rankin House in Northfield.  We are unsure of the event date or purpose, or location; could be Social Hall at the Hermon campus, and a banner celebrating turning 50 appears in on photo.  Birthday party 1997?  Reunion 2000?  Any helpful ideas are welcome.  Rankin House was an "overflow" dorm 1964-65, with Nan and Gail Watson Nozik plus several underclass students.  Nan and Gail are listed in the Highlights yearbook as connected with East Marquand-Rankin House.