The correct answer is $\boxed{\text{B}}$.
The air pressure in the engine and brake van of a goods train with 58 N boxes shall be 5.0 kg/cm2 and 4.2 kg/cm2 respectively. This is because the air pressure in the engine must be high enough to provide the necessary power to the train, while the air pressure in the brake van must be low enough to allow the brakes to function properly.
Option A is incorrect because the air pressure in the engine must be higher than 4.1 kg/cm2 in order to provide the necessary power to the train.
Option C is incorrect because the air pressure in the brake van must be lower than 4.5 kg/cm2 in order to allow the brakes to function properly.
Option D is incorrect because the air pressure in the brake van must be lower than 4.7 kg/cm2 in order to allow the brakes to function properly.