If I understand your problem, you need to send the pulses from station B back to station A over a 10 mile distance and you prefer to do this by Ethernet, since you already have a network setup, correct?
If so, then I think the PLC at station B is confusing the issue. You need to send a pulse, but it doesn't have to be done with a PLC.
Couple of suggestions:
1) Digi International provides wireless devices that do this. They have units that essentially perform "wireless cable replacement." That is, you can input a digital signal at one end, and it is recreated at the other end. I think they support up to 40 miles range. The Pro 900 is probably what you need, but you can contact them for help at digi.com
2) A small PC to sample the pulses, and communicate them over Ethernet to a mirror PC at the other end that regenerates the pulses. PC can be something tiny like a Beaglebone or PC104 system.
3) A full custom device. I designed something like this for a pump station many years ago. A monitoring box read a few output from a PLC and when one changed, it dialed up its "mirror" box over a telephone line via modem and mirrored the output state of the PLC. The data only changed every few hours, so using the phone was OK. However, you should be able to find something off the shelf for your application
Lyndon