Recently there is an oily sticky coating on one rear wheel, what is this the result of?

 

Assuming it was not something you picked up from the road, It can only be Brake fluid or 90 weight oil from the axle. Most likely it is brake fluid.
1st Check the brake fluid level under the hood.
2nd clean it up. Take off the wheel Clean everything especially the entire brake caliper area with Brake cleaner and a stiff brush and wheel with plain soap water or maybe just wipe clean with a rag if its not real bad.
3rd. Look around for any new wet spots.
4th Drive it a few miles, take off the wheel, look all around the brake caliper area look for a new wet spot.

 

Thanks for the thoughts!

Turns out it was residue from the brake pad as the pad was worn down alot.