A 5V @ 1A wifi surveillance camera placed 50ft away (indoor)
There are two ways to approach this

1) Use thick enough wire to run 5v

2) Accept a voltage drop and work round it, with easy-to-obtain parts

Run 5V

How much current does your webcam use? It may say '5v 1A' on the side, but have you measured it? It's probably less. But let's assume worst case of 1A. 

How much voltage can you allow to drop to the camera? Let's guess at 0.5v, as 10% of your supply voltage. That may be too much, but let's do the sums for that as a baseline.

Dropping 0.5v at 1A requires a loop resistance of 0.5ohms or less. As your measured loop resistance is 11 ohms, you need 22 strands in parallel. 

It would be more sensible simply to use thicker wire.

[pause] You've just updated your OP to reflect the above calculation, with slightly different starting assumptions, but the same general conclusions[/pause]

Work with the voltage drop

Your camera requires 5 watts. To deliver 5W into 11 ohms requires 7.5V. So a bit more than 15v supply at the house driving an 11 ohm loop and a voltage converter at the far end would be able to do the job. 

Laptop adaptors (typical voltages around 19v) are easy to come by these days. You would need a buck converter at the far end, which are also easily and cheaply available, with an input range that covered at least 7 to 19v, and an output of 1A.

Choice

The cost and hassle of buying and drawing thicker wire, versus the cost and hassle of leaving the existing wire there, changing the driving power supply, and buying a remote voltage converter.

Notes. It's probably wise to increase the wire gauge further for option 1, as your 5v supply might be on the low side of 5v, and the camera a bit touchy about whether it gets 5.0 or 4.9v. An extra 0.25 or 0.5v drop could be the difference between it working or not.