Top one of the essentials, IMO, is water

Before retirement, I had some lockable drawers in the office. So, I made a cache of essentials in case I was stranded in the office and couldn't go back home due to the weather or whatever. I stored and rotated a few bottles of water and biscuits/crackers that I bought from the cafeteria. In addition, I stored a few other items that would be helpful if I had to sleep in the office.

There was also a small bag containing flashlight, extra batteries, lighter, multitool ..etc. just in case I had to walk

Never needed them but was good feeling to know they were there.
Funny thing is , in the same drawers I kept a small personal tool kit, which has seen tons of use in the office.