What is the ruling on a woman uncovering her hands and feet in front of a driver or worker, while covering her face with only a sheet?

It is not permissible for a woman to uncover her hands or feet in front of a driver, a worker, or any other non-mahram, because they are part of her awrah (private parts that must be covered). Likewise, the veil covering the face must not be transparent such that the skin beneath it is visible. It is also important to warn against the impermissibility of unlawful seclusion (khalwah) with a driver, a worker, or any other stranger.