Circuit for safety button which turn off relay power supply
First of all: safety must be designed into the application and not added later. You simply can't graft on a safety circuit to a machine.
In safety the KISS principle rules, followed by redundancy, which is somewhat the total opposite.
If you put filters, isolators, whatever, you add failure points to the chain and the resiliency/reliability analysis becomes much more complex.
After that consider that mechanical is better than electromechanical that in turn is better than electronical. Software is almost forbidden except after extensive (and expensive certification). Safety in high power lasers is done with a steel and concrete block in the beam path, not a transistor switching the laser off (well, it is switched off, but it could fail and the shutter is the safety).
From what you tell your circuit is already at quite a low point of safety, since there is only one switch and only one relay: unless they are of exceptional quality (i.e. safety rated) if the switch breaks or one contact welds there would be no safety anymore. That's of course all depend of what that safety protect against. Without schematic and the risk analysis of the scenario it's difficult to say.
If you are worried about noise then better put a whole regulator dedicated to that line, it's cheap. Consider that a typical door interlock uses at least three guided contact relays (they cost 5-10 times more than the standard ones)