Out of those things listed I'd opt for Sanitation laws and plumbing as the most effective change affecting the health of people living in large towns or cities. Before it became commonplace there were always frequent outbreaks of cholera. When Londoners stopped dumping their sewage and other waste into the streets and alleys and the huge network of sewers and drains were put it, the quality of life of, what was then, the greatest city in the world, went up in leaps and bounds.
We've still got a long way to go with this, of course. Londoners promptly started draining all that waste water and sewage into the River Thames.
As for the others: pencillin saved millions of lived but became the forerunner for today's 'super-bugs.' Airconditioning is good but costs the world in pollution as we rip up our coal reserves to keep them going.
Pasteurization, yes. Good. But not as big a deal as sanitation. Dental hygiene. Yes, Good, but once again, not as worldly effective as No3.
Grog. Well...Like many it is both a pleasure and a curse. Won't go there.
Soap and water. You can actually take a shower and a bath witout the former, so it is not an essential.