The correct option is C to
Here, 'to' is correct because it is used to show a relationship between one thing and another, here it is between the person and the hotel.
'On' is incorrect because it implies in or into a position covering, touching or forming part of a surface.
'Off' is incorrect because it implies away from a place; at a distance in space or time.
'At' is incorrect because it is used to say where something/somebody is or where something happens.