Age doesn’t matter. Good examples are Elizabeth Hurley, Susan Sarandon, Bernadette Peters, Bebe Neuwirth, Stevie Nicks, Valerie Bertinelli, etc.
They all have long hairstyles and they all look fantastic. Older women can wear long hair styles as long as they flatter them.
There is a wide variety of looks and hairstyles for older women. You can have simple hanging lengths or wear the hair up or a simple, smooth twist.