PLB's etc are all very well but you still have to survive the night, so:
1) Carry a proper sleeping bag and a mat. They don't weigh a lot and will go a long way towards keeping you warm.
2) Carry proper firelighter's. That means Esbit or simular. Minimum of 4 - 6. I have used sterno and firepastes. Not impressed with them. They don't burn hot enough or long enough.
3) Calories and lots of them. Hot chocolate, Soups, Bars of chocolate, Coffee or tea according to your tastes. Sugar. I also carry instant noodles. Not the worlds greatest food but quick easy and a great moral lifter.
4) Matches. NATO lifeboat prefered. Drop one of them on a firelighter and you will have fire.
5) A shelter. Heatsheets are good for this. Getting out of the weather is priority number one.