There's conflicting information on if the evacuated folks would be kept for 14 days in quarantine, or as little as 3 days plus "voluntary self quarantine at home". The assumption here is that the virus incubation period is 5-7 days, so 14 day quarantine is supposed to be effective. But you should be prepared just in case. In worse case we may have to stay home.
At minimum you should consider stocking drinking water, food, medicine, and other necessities for at least 2 weeks. In addition, you should prep 72 hours "bug out bags" in case if you had to leave your residence. The Red Cross web site has recommendations on what you should prep for 3 day pack. Don't forget cash, in an emergency the bank will not be open, and the ATM may be empty or not running (power outage).
The LDS Church (I am not a member) recommends long-term emergency supply of food, water, and funds for at least 3 months. They have many articles on their web site if you're interested, they also sell freeze dried #10 can foods with 30 year shelf life at very reasonable prices.
Many people will run to local military surplus stores to buy stuff. We have many in the area, including Major Surplus and Survival in Gardena, Prep & Save in Upload, and All American Military Surplus in Fullerton & Stanton. Those stores are good for some stuff but I would caution against buying stuff like mil-surplus gas masks/filters/etc. The old military style masks have poor visibility and the filter cartridges do expire. Don't get hooked into buying some NBC kit with old gas mask and expired filter/iodine pills.
Remember -- before you spend money, look around the house. You may already have the items that you need.
