1. Tent (2 person tents are better than the 4-6 person tents because they are lighter and weight can be distributed.
2. Sleeping bags
3. yoga mat
4. Avoid blankets/shawls of any sort. I prefer jackets and socks for warmth and they save weight too.
5. Matchsticks. remember to distribute them in 2 different bags to prevent them getting damp
6. Liquor/cigarettes should be avoided… cigarettes are a fire hazard and liquor can cause dehydration
7. Spare set of socks is a must. It is always good to have an extra t-shirt, shorts/trackpants
8. Odomas cream for protection against leeches and a can of baygon spray (cockroach version) for the sleeping area
9. Swiss army knife
10. MTR Packets (I could never cook a decent meal during treks and sometimes we forgot to bring the right ingredients or the water is scarce making things undercooked. however food for 3 persons is going to be consumed in just one meal. BTW don’t be surprised to know that breakfast and evening snacks are a meal in itself.
11. Torchlight (1 for every 2 persons): Most people forget to pack it.
12. Hat/cap + sunscreen . cannot emphasize enough.
13. Jacket, gloves and whatever you need to keep yourself warm.
14. Energy bars. chikki, chocolate, sugar candies are always welcome
15. Avoid fruits and vegetables. Carry things which provide high calories, can be eaten raw and completely (mangoes with their big stones are strict NO NO)
16. Electrolyte. I would recommend 4packets per person per day.
17. Fully charged mobile phones. One can get cell receptions in the unlikeliest of the places. Plus they are a good source of music.
18. Camera but avoid tripods.
19. Medicine kit esp. band-aids
20. Bags: Typically I would recommend a guy carrying a full 10-20L backpack while a girl carrying a simple school bag. Call me sexist but any other combination and girls will slow you down.
21. Shoes: Need to be comfortable, waterproof, with good grip.
22. 2 1-L plastic bottles (no metal bottles no thermos flasks) If you can get a trekking sipper go for it.
23. Walking stick. There are aluminum trekking sticks. Expensive but worth it esp. on the way back.
Last but not the least distribute your items across multiple persons. This way even if one bag gets lost/the person carrying it becomes slow the whole group can still manage it.