1994 Honda Civic Oil in Plugs

I went to change the spark plugs and found that there was oil in one of the spark plug sockets. So I’m asking what this means. Is the problem the head gasket, valve seal, spark plug tube o-rings, or the piston rings?

It’s NOT a head gasket problem…it’s a valve cover gasket problem. There are seals around the valve cover that mate the valve cover to the head. To fix this get a Valve cover gaset ket. It will include ALL the seals and gaskets.