Sleeping bag (rated to -30°C) plus inner (light fleece or micro fibre), foam or inflatable mattress (Thermarest etc.).
Thermal underwear (vest and long johns), two fleece tops, Goretex jacket, down jacket, warm mountain trousers, 6 pairs of socks, tee shirts, shirt with collar, warm hat / balaclava, warm scarf, 2 pairs of warm gloves, warm slippers / camp footwear for evenings.
Warm walking boots that you have worn in - they should be sturdy, with some insulation, a good sole and preferably a removable insole that can be dried out at night, like Sorrel and Baffin, head torch with new and spare batteries, walking poles (with sharp points).
Water bottle (isothermic, at least 1 litre), sunglasses (2 pairs), spare laces for boots, washing bag with toiletries, towel, pocket penknife, mending kit (needle and thread), document wallet (for passport, plane ticket, insurance documents, money), reading and writing materials, binoculars, etc.
Diamox (altitude sickness), painkillers (paracetamol), anti-inflammatories (ibuprofen), one-week course of wide-spectrum antibiotic, anti-diarrhoea and
anti-constipation pills (Sennekot), light sleeping pills, plasters, bandages, antiseptic cream, anti-mosquito ointment, sun cream and lip salve, water
purifying tablets, earplugs, eye lotion, tweezers.
Your own medicines.