Being one of those subdivision dwellers myself I'd considered that question myself. The only thing I could come up with was a kind of panic room. Like in the movie of the same name. A reinforced room or two or maybe a hidden room somewhere in the house.
Only problem is it probably wouldn't work for long term or against a large number of people, or fire, or a number of other things I haven't even considered yet.
I'd like to hear other opinions myself as I can't come up with any long term viable plans.
You might consider an under ground saferoom.
Most subdiv houses are built on crawlspace foundations, with plenty of room underneath.
Dig a pit directly under the closet in the master bedroom about four or five feet deep and pour a 4" thick concrete floor at the bottom, thickened around the edges to about eight inches. Then lay up some block walls to the underside of the floor system, and fill them with concrete at least to the level of the dirt. After backfilling, spread the excess soil around in the crawlspace. This should give you about six or seven feet of head room in the shelter, depending on the height of your foundation. Be sure to leave and escape hatch into the crawl space, just in case.
A simple scuttle hole in the floor above, covered with carpet to match will work for the entrance. A throw rug on top will also help to disguise the carpet seams at the hatch.
Then it's a simple matter of storing your "mission critical" supplies in the under floor space.
When the poop hits the prop, hide in the underground space until the threat passes. Bad guys can roam at will in the house and if you keep quite, they will probably pass you by as there is usually not much of value in a closet and they will spend little time in there. They'll be more concerned about food and weapons.
You will also be safer if they decide to "recon by fire" as you will be below the line of fire.
Down side is that if they do find you, your toast, unless you can escape into the crawlspace and exit out of the house. (A locking mechanism on the hatch, actuated from inside the shelter, will reduce the chance of this.) Or if they fire the house for gits and shiggles, in which case you'll have to exit the shelter through the crawlspace. Note: most crawlspace access panels are latchable from the OUTSIDE, egress from the crawlspace may not be possible until this issue is resolved.
Another problem is that all the digging work will have to be done by hand and that will suck, but it can be done on the sly and nobody will be the wiser.
Cut the access in the floor first, then all tools and materials can be brought into the house and then down into the work area.
If you have an attached garage to stage from, concrete mixing and working will be much easier and out of sight.
Oh, and when diggin the pit, don't undermine the existing foundations of the house.
Just a thought.
