From wikipedia

The Hiltons' last public appearance was in 1961 at a drive-in cinema in Charlotte, North Carolina. Their tour manager abandoned them there, and with no means of transportation or income, they were forced to take a job in a nearby grocery store.[2]

On 4 January 1969, after they failed to report to work, their boss called the police. The twins were found dead in their home, victims of the Hong Kong flu. According to a forensic investigation, Daisy died first; Violet died between two and four days later.[2] They were buried in Forest Lawn West Cemetery.