It would be highly beneficial to know if the fault code goes with the sensor. If the code always sets for the right side then you know it can't be the sensor. If swapping the sensor from one side to the other changes the fault code, then you know the sensor is bad.
It's hard to say what is going on without seeing it and what actual code is setting. If it's setting a sensor circuit code, that means the circuit from the processor in the ABS module to the sensor is open. This could be the module, sensor, or wiring in between. If it's setting a speed sensor failure code then you know the electrical circuit is ok and something else is going on.
If it's a circuit code it can only be the module, wiring, or sensor. If swapping the sensor doesn't change the code, then it's wiring or the module. They need to load test the wires to the sensor in this case, not just checking them for continuity with a voltmeter.
If it's a signal failure code then it could really still be any of these things, but the wheel bearing is a possibility too. The tone wheel that the sensor runs off of is inside the bearing, if the bearing is loose then it will change the air gap between the sensor and tone wheel and affect it's signal.
If swapping the sensor to the other side of the van changes the code, the sensor is bad.
If swapping the sensor doesn't change the code then rule out the sensor. It could be the wheel bearing, wiring or module. If the bearing is tight it should be ok.
If it comes to this point I would recommend load testing the wiring with a headlamp or fog lamp bulb. They should be familiar with this procedure and may have already done it. If the wiring checks out and so does the sensor and wheel bearing, then the module is going to need to be replaced.