remote rf

Hello again. Here I go again embarking on another project, that I know little about and the new technology available.
My objective is to have a transmitter on a car, emit a signal to a receiver, and to then check the receiver's proximity to the the car. If too close, an alarm goes off.
Also the receiver must be able to also transmit a signal to the car to deactivate a switch.
Maximum range of thirty feet.
I just need ideas. Well maybe some help too.
Would Zigbee protocol work here, and if so how to implement?

Thanks