Here's a generic list to get one to think about what you actually have on hand to grab and toss into a pack on the way to the front door...just what you'd want for a couple of days, but thinking back to the basics for survival essentials:
Shelter (emergency blanket, tarp, fleece blanket and/or clothes, gloves [leather or cotton, insulated or not]...clothes, technically, can be shelter, but should include additional layers for changing weather...don't forget that wool insulates even when wet);
Water (filter/purification bottle, iodine tabs or other chemical purification, bottled water...but definitely have a day's worth ready to go, plus means to purify more at any opportunity);
Food (bars, peanut butter, anything high-calorie that they can eat on the go w/o cooking...3 days minimum supply);
Fire, to eventually be able to cook, and obviously to keep warm during poor weather or cold nights (striker and tinder, magnesium/striker, several dozen water-proof matches...lighters don't work well if they get wet...learn to make friction fires);
Basic first aid (even if it's just a few self-adhesive flex-fabric bandages, pads, tape, burn cream or triple A/B, gastrointestinal relief and pain meds/fever reducers if desired...it's better than nothing at all);
Sanitation/Hygiene (1 roll TP and any other personal hygiene items you would prefer not to be without);
Lighting (candles [aid in fire-starting as well], compact single-cell LED flashlight and spare alkaline batteries...a higher-powered compact LED flashlight and spare batteries, if desired...both of metal construction with o-ring seals for water resistance and durability);
Tools (multi-tool with several blade types, pliers, wire cutter, wood-saw, drivers, etc, or at least a lock-back knife with partial serrated blade and fine edge combination...a pocket sharpening system is nice to have on hand as well);
The above would probably be the minimum I'd want to have ready to go for a LMB.
Anything that has multiple uses for survival should be considered, as they save weight and space. If one is interested enough in having items on hand, maybe they will be interested in having it packed and ready to go at a moment's notice...it just doesn't make sense not to...just get it ready and you don't have to think about it when you're likely going to be a bit panicky as it is...one less thing to think about in the end.
In reality, one should consider expanding this list to their preferences, add weapons, small cooking gear, dehydrated/freeze-dried foods or whatever, and just having it in a pack, ready to grab and go.
I will admit that having all off the gear I possess didn't happen overnight, and for those who would want just the basics, it doesn't take long or cost a lot of coin.