did the cop ever got back to his time ?

It did not show him getting back.

"Titus pullo is not afraid of any bastard with a dogs head on him"-Rome

There was no final episode that actually ended the series. The TV show was discontinued before it got as far as the producers had planned. The last episode is a regular story that ends as if it will be followed by another season- but we all know the show was cancelled after only the second one. It can be assumed that Darien Lambert returns home to the future off-screen (which was also the case for other time-travel TV shows such as "The Time Tunnel" from the late 1960's and "Voyagers" from the early 1980's).

Well since he can go home anytime he wants I would assume yes. He is only staying to stop the criminals.