It might be a little more difficult with more than one entrance/exit but here’s what I did last year when we had bees coming and going above our front door. I set up a shop vac with a few inches of water in it and secured the suction hose at their access point. Turned on the vac and let it run for a couple hours. Any bee coming or going got sucked up and drowned.
I have an office in a loft area above our garage. One outside wall is all cedar shake, which looks nice but makes it very hard to detect the entry point of an insect infestation.
Last summer yellow jackets had gotten into the wall itself, because they started appearing in my office a half dozen to a dozen at a time while I was trying to work. They were also congregating inside the garage. I have a doorwall to a small balcony in my second floor office which the yellow jackets would swarm against, (the glass of the doorwall) trying to get outside again.
I got a small piece of wood block and methodically smashed them against the glass one at a time for weeks, until I saw no more. I literally must have killed a hundred of them or more, one at a time. I had heard that smashed wasps release a chemical that alerts other wasps to danger but this did not seem to be the case with these YJs fortunately. Amazingly I never got stung during all that.
Also fortunately, they haven’t appeared in my office again this year (yet).
If you figure out what kind they are and what they eat, some poisoned bait might work on the cheap. A lot of pest wasps eat meat so perhaps some dollar store boric acid (generally considered safe for people) mixed with a few ounces of ground beef might do the trick.
If it’s done late at night, wasps are sluggish and not prone to reaction well past nightfall. It’s also the right time to do it simply because all the wasps will be in the nest to be easily slain.
Is that the total area of the decking or just the area of the deck you think the nest is in? If it’s that small, I would get a roll of clear plastic or some painters tarps. Close off all 4 sides and everything on top except for one board. Take the screws out of the board during the day. At night, lift the board, drop in your bombs, drop the board back in place and put a piece of tarp over it. Maybe have something heavy to put on the last tarp piece, a couple of wood pieces or bricks.
Well, I already had like 3 or 4 cans of foaming wasp spray at various levels of fullness (I buy a can, my wife puts it away somewhere I don’t think to check and I buy another can, and so on). So I tried the foaming stuff first since it’s what I had.
I blasted the area between the slats and used probably the equivalent of 2 full cans into the space underneath. But, like @Joey_P warned, the foaming effect isn’t that robust, and didn’t fill up the space underneath the deck like I’d hoped. I’m still seeing wasps come and go, though maybe not as many as before.
I just ordered the Tempo 1% dust that @Turble recommended along with a long-handled duster. I figured that would be better than the fogger since I have a lot of nooks and crannies around my house where the duster would probably work better than a fogger.
Keep in mind that the stuff works on ants, roaches, bed bugs, all sorts of creepy-crawlies.
Throw a couple of pennies or small screws or nuts or something like that in the duster to shake it up. The stuff goes a long way so you probably won’t need fill up your duster – just be sure you remember where you put it for next time. 
This.
Very cost-efficient.
When I first moved into my current location, in 2012, wasps built a nest under my deck chair, and kept rebuilding them whenever I knocked them off. Because I suspected (correctly) that mine wasn’t the only one, I called the rental office, and they sent an exterminator out who sprayed a repellent hormone on the bottom of that chair so they wouldn’t want to return.
Nine years later, they still haven’t. I’ve had other insects, and seen wasps, but not right here.
I second calling one.
Nothing kills bed bugs.
Ok, obviously some things do but I had them once and holy-mother-of-god were they hard to kill. Really quite shocking. So bad that I still have a little PTSD from the experience (not kidding…I do not want to overstate it or make light of people who have serious PTSD but I really do still twitch and jump at some things 10-years later). They are unbelievably tenacious little fuckers. It took me weeks to be rid of them and I only ever had a few.
Yeah, there are chem-resistant bedbugs these days. AIUI, the gold standard for eliminating them, the “nuke the site from orbit” solution, is to wrap your house in tarps and bring in industrial-sized space heaters (powered by a trailer-mounted generator that can deliver enough electricity) and raise the temp inside your house to somewhere over 125 degrees. It’s the only way to be sure.