My mobilehome waterline goes from water heater to water meter to shutoff valve to underground and there's a plug in rod at the pip coming from ground what is this? Is it home owners responsibility or the same as water meter?

That sould like an electrical ground rod... if it is it has nothing to do with keeping pipes from freezing. Anything to heat the pipes will look like a tape wrapping around the pipe.

Are you talking about a rod with a t-shaped handle on one end (to aid in turning it), that can be placed over a valve 3 or so feet down in the ground and allows someone to rotate the valve to turn it on and off, possibly?
A type of valve wrench of which I have seen many times but never knew the official name.