There are number of options for communications and you can get them in very small packages (the size of a quarter is quite possible).
The first issue is power, how long do you want the link to be active? Drone flight times are rather short, so perhaps that's not a huge problem, but you'll have to think through the various use cases to come up with a solution that takes into consideration how this will be recharged etc... For short link distances NFC would work well and wouldn't require any power source, but at 50 feet that's impractical.
The next issue is positioning, how tightly do you want the drone to track the user? Of course you could use GPS in both etc... but that's expensive and power hungry. If you don't need super tight tracking you might get away with an RF beacon and a few receivers on the drone (to triangulate position).
It's all about the details. I would recommend you create a detailed requirements document that explains what you want to do (desired: link distance, link time, recharge time, positioning/orientation accuracy, etc.) and then get input from technical folks on what something like that would take to implement...
One option that occurs to me is that you might be able to use a cellphone and use the on-board GPS there to correlate with a GPS unit on a drone and then simply write a small app to communicate with the drone (perhaps over WiFi) and simply relay the desired GPS coordinates for the phone as the next target for the drone. That would be a much simpler implementation and wouldn't require any hardware (aside from finding a drone with both GPS and WiFi, which it seems would be pretty available at a reasonable price). And, most folks have cellphones, so all you need then is a pretty simple app, and with the cellphone interface you could then make it do other things (adjust it's height, have it trail or lead you... etc).
I'd be surprised if this didn't already exist.