The answer would be B. Lower.
Explanation:
This is because Force between two bodies is directly proportional to the mass of an object, but inversely proportional to the square of the distance between them.
So if the mass of the moon becomes twice, the force would also be twice as strong. (2 F ) , but if the distance is doubled, this force (2 F ) would be quartered ( 2F/4 = F/2 ) which would be half of the original force F.
Hence if the force is halved, the tides would be lower.