There are lots of websites and references as to what should be placed in emergency supply kits, please see the links below for suggestions.
Important things to consider are supplies for your pets, copies of prescriptions, and legal papers such as copies of vital documents in a waterproof bag or wallet (passport, emergency contact list, insurance/bank info, and family photos for identification purposes). WATER is of course critical. A test or trial run can be illuminating.
After you establish an emergency supply kit, it's important to remember to renew or replace items whenever you change your clocks for daylight savings time.