It has been said that the best defense is a good offence. This is the main thought behind a few forms of martial arts and various military leaders around the world but you can easily apply it to your survival situation to ensure that no one will even consider messing with your or your loved ones.
There are situations that may arise from time to time during an emergency situation that might leave you with absolutely nothing. It is these times that learning how to make and use improvised weapons are more than worth the time it takes to think with some forethought.
The simplest and quickest improvised weapon that I can think of, is any thing that you can pick off of the ground. This includes sticks and stones which can easily break bones and also includes bricks pipes and other construction materials.
A construction site can be a valuable place to scavenge from in a time of emergency so keep that in mind while the rest of your community is engaged in tribal warfare at the local grocery store.
If time is on your side and you have already taken care of the essentials of food, water and shelter, you might want to consider taking the time to properly build yourself a self defense weapon. This is where your own creativity is going to have to come into play. Use what you can find or what is available to you to create the best improvised weapon that you can. Just make sure that you know what you are up against, a sharpened stick is no match for someone with a gun or machete.
If you are looking for ideas about what kind of improvised weapon you should make then I suggest that you think like a cave man. Make a spear, that should be enough to keep most unarmed attackers at a good distance. A throwing stick is also a great pre-historic weapon but the only problem with using one for self defense is that they are a single use weapon and are more suited for hunting.
If you are unconcerned about attackers and your neighborhood is a peaceful place full of generous and kind people that are willing to help each other out in times of crisis, you are still going to want an improvised weapon. Not for defense of offense, but for hunting.
If you are the only person in town with a bow and can take down a deer to feed your local community, you are going to be well loved, and also have a great commodity that you can easily trade for other goods and services.
With all of those things in mind, the only advice that I can truly give is that the best weapons are the ones that get the job done. So choose wisely and remember that even though an improvised weapon is a valuable tool, diplomacy is far more powerful.