Here is the circuit.It has a continuous ripple of 200mV on Power lines.
As Nigel stated this is probably measurement error. To check you can leave your scope ground on ground where you have it now and probe the same ground lead an inch away. It should obviously be zero since it is just a wire so any reading is measurement error. You can also measure the frequency of the noise. If it is ripple in the classic sense it will be at 100 Hz. If it is at some other frequency (say 50 Hz.) it is probably noise pickup on your scope leads.
Does the 7805 not have enough load to regulate?
The 7805 has a built in minimum load.
I added a couple of things to your schematic as a precaution not related to the ripple. One is to have the relay current go straight back to the power supply and not thru any of the logic ground.
Two would be where the snubber would go if the relay load is a motor or something else inductive.