All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
His eminence Shaykh ‘Abdul-‘Azeez ibn Baz, may Allaah Almighty have mercy upon him, answered a similar question, saying:
The driver and the servant are like the other men. A woman should wear Hijab before them if they are non-Mahrams. It is impermissible that any of them sees her face or sits with her in seclusion, because the Prophet, sallallaahu ‘alayhi wa sallam, said: “If a man and a woman (who are not Mahrams to each other) sit alone in seclusion, then Satan is their third,” and because of the general indication of the texts that prove the obligation of Hijab and the forbiddance of displaying adornments and exposing the face before non-Mahram men.
Allaah Knows best.