@KeiosKod @TetraSky
MC can't hear ghosts' voices, but he can watch their reactions, so she probably just lightly nodded at his 'do you want me to go and buy...' question.
though it's not confirmed whether ghosts physically eat, they seem to like the smell of food: https://mangadex.org/chapter/897306/1 https://mangadex.org/chapter/897314/2
@KingRagnarok
as AnonMan88 mentions, https://mangadex.org/chapter/907557/1 she won't go away from the car