Thebesian valve is present between

The correct option is C coronary sinus and right atrium
Coronary sinus drains the deoxygenated blood from the heart muscles to the right auricle. To prevent the backflow of blood from the right auricle to the coronary sinus, the opening of the coronary sinus is guarded by the Thebesian valve. So Thebesian valve is present between the coronary sinus and the right atrium.

The opening of the inferior vena cava into the right atrium is guarded by a valve named Eustachian valve.
The opening of the superior vena cava into the right atrium and pulmonary veins into the left atrium are not guarded by any valves.