My home is on a public utility water system and the standing pressure at the bib closest to the water line into the home sets at 42 psi. However, when we either flush a toilet or turn the shower on in the master bath I get a [B]significant vibration on the utility water line connection to my home and the pressure drops to 22 psi. All of the fixtures in the master bath check out and there are no leaks. Does this indicate that the home pressure regulator located at the utility water connection is bad or going bad?

That is an indication of a failing PRV. Go to the PRV and have someone flush. Should hear it. Sometimes a well placed tap with a hammer will reseat the diaphragm. Don't hit the plastic cap, if so fitted and don't smack it hard. PRV's, unless fully soldered in are easy to replace, typically just having pipe thread and union fittings. They are mostly factory set at #50.