"Can you program the 8051 to recognize the distance between the transmitter so that if the transmitter come closer"

I do not quite understand, are you talking about 1) a fixed position transmitter and a portable receiver (in the blind persons hand) or are you talking abt 2) a transmitter and receiver measuring distance similar to Radar?

In case 1 it is a matter of signal strength, and a uC would be overkill.
In case 2 do a search here on "distance".

Erik