What is the ruling on a woman working who goes to a workers' workshop accompanied by a driver alone, in a workshop located on a mountain an hour and a half away from her state, and all the workers are men?

If a woman's work exposes her to riding alone with a driver and traveling without a mahram, then her work is impermissible. This is because a woman riding alone with a driver is considered khalwa (unlawful seclusion), just as her traveling without a mahram is not permissible.