I agree - at a minimum each hiker should have
a pack
a water bottle
a jacket
And the leaders should have
faK
lights
map/compass
I was thinking that either the leaders should carry enough large "trash" bags so there would be one for each person, or distribute one to each person. The bags could be used, with head and arm holes cut, as a poncho, or with just a hole cut for the head as a hasty shelter. Or it could be used for the trash.
We then need to also add a knife or scissors to the list.