ABS sensor issues

Symptoms:

ABS light on.
Brake light on.
"Service Brake System" on the display.
Speedometer not working.
Transmission not shifting properly.
Poor idle.

Took it to parts store and had codes read and it came back with the following:
B0100 Electronic front sensor malfunction.
C0055 Speed Sensor Circuit.
C0300 Rear prop shaft speed sensor missing signal.
P0502 Speed Sensor A circuit low input.
P0502 Speed Sensor A circuit low input.

I figure it is a sensor issue but not sure which of the three sensors or all need replaced.