Rear ABS light on?

I have a yellow ABS light on and my passenger rear wheel has grease coming out of the inside of the wheel drum. I just bought the car so I have no idea how long it has been there but it is a black film. It does not smell like brake fluid and the fluid level is not going down.

1. Is this from the axle seal?
2. Is it the reason the ABS light is on?

Thanks