D&D 5E Monster group stealth

[Plaguescarred]

A green hag and 4 bullywugs are lying in wait in a dimly lit temple. They plan to hide and ambush the unaware players as they enter. How many stealth rolls should the DM make? Does each creature make it's own stealth roll? It seems likely that at least one will roll poorly if so. Does the DM make a group check with all the creatures? Does he roll individually for the hag and a group check for the bullywugs? Does he roll once for the hag and once for the group of bullywugs?

I'd have each monsters hiding make a Dexterity (Stealth) check that would be contested by the Passive Perception of the PCs.

Group checks are made by everyone in a group as well, but works best when they contest the ability check against a known set number (DC, PP) since the whole group only succeeds if at least half the group succeeds. I will only use Group check against set DC task, or in the case of Stealth, against' the PP of same type creatures the hiders are trying to hide from i.e the PC spot a group of goblins coming in the distance and try to hide to lay an ambush. Group check doesn't work well against different target numbers like Passive Perceptions of different creatures.

 

[Satyrn]

It's striking that every answer is different.

Aye. I dont even know what I'd do, probably just set a DC and roll for surprise when the ambush is launched. But I would also wait a few beats between when describing the PCs approaching/entering the kill zone. and when the ambush is launched; this to give them a chance to actively search for the danger if they want to bother.

The actual rules I wind up using are less important to me than trying to give the players the opportunity to foil my plans. If they see they have/had that chance, I believe nearly any halfway reasonable mechanics-ruling will be acceptable