Answer:
z-wave
Explanation:
Based on the scenario being described within the question it can be said that the best device would be a z-wave type of device. That is because z-wave devices have an effective range of about 100 meters which more than meets the company's requirements and operates on an RF band of 908.42 MHz, and therefore will not interfere with 2.4GHZ bands, which both Bluetooth and ZigBee devices will.