Here is all you need to know for the 2017 christmas event:
Need a party. (no min players)
^ Taken from http://wiki.rebirthro.com/wiki/2017_Christmas_Event
Now for the Children locations according to your gifts:
^ Credits to Rozenskye for the mob drop list.
NOTE: Once you see sasquatch and marin mobs in your map, you have already completed acquiring all the quest items and was warped (forced) out from the event field. Proceed to talk to sarah and get the gift box to deliver to the children.
As a completion reward, you will get a "Christmas Gift (2017)" box. Below is a list of possible items you are able to obtain randomly (list contributed by players on main chat).
Santa Mask 
Christmas Cake Hat 
Christmas Cake Ring 
Artist Hat 
Nyd Hair 
Rainbow Confetti 
Winter Scarf (2017)
White Scarf (alternate colors: Red,Pink,Cyan)
Random mob cards (Muka, piggy, zombie, megalodon) <-Probably works like OCA
Merry Christmas everyone !