The answer to your question is,
You would need to put an updated first aid manual, emergency phone numbers, sterile gauze pads of different sizes, adhesive tape, adhesive bandages in several sizes, elastic bandages, splint, antiseptic wipes, soap , antibiotic ointment , antiseptic solution (like hydrogen peroxide) , hydrocortisone cream (1%) , acetaminophen and ibuprofen , extra prescription medicines (if the family is going on vacation) , tweezers , sharp scissors , safety pins , disposable instant cold packs , calamine lotion , alcohol wipes or ethyl alcohol , thermometer , tooth preservation kit , plastic non-latex gloves (at least 2 pairs) , flashlight and extra batteries , a blanket ,mouthpiece for giving CPR (you can get one from your local Red Cross).
There's quite a lot, but you just have to be ready in case something happens! <3
-Mabel <3