This question is prompted by a real accident, in which a young, healthy and experienced hiker I knew was found dead from hypothermia ridiculously close to civilization.
The assumptions behind it: a hike in winter conditions in a temperate climate zone (Europe), can be below or above the tree limit. The hiker plans to sleep in serviced lodges, or to go up and down on the same day, so has no tent or cooking equipment along. It is not too far in the wilderness - if the hiker calls a rescue service and can somehow submit exact coordinates, rescuers can reach the hiker in time. The hiker has no experience building a shelter out of branches, or some kind of iglu-like construction. The hiker envisions an easy walk along a marked path, but the weather turns problematic (e.g. a snowstorm, or fog) and he or she loses the way. Cell phone coverage might exist, but is likely to be patchy and weak, and probably without mobile Internet or reliable GPS.
I saw that there are questions about actions one could take, but I would like to ask for a list of items one would have to carry to prevent hypothermia and death, and have a reasonable cost (most people I know cannot afford a satellite phone, for example). This would include items which make it easier to find one's way again, to communicate with rescuers, to prevent hypothermia in the short term (like the energy bars mentioned in the linked question) and to preserve enough body warmth (or maybe there is a heater option?) to survive for a whole night, if needed. Also, the package should be small enough to allow for an enjoyable hike when everything goes well.