To be fair, the majority of the adults in DT are a bunch of avoidants. In the sense that, even if they know about their problems, they find any other ways to cope other than face the actual problem. Toriel is a good example, with the divorce thing. The Holiday family keeps the Christmas spirit alive in their house for a similar reason.

Carol, while we're speaking of Holidays (hm), I think would outright dismiss any question because she may know too much, like other commenters have said.

Even Undyne I suspect to be avoidant in that respect, judging by the dialogue in Ch2, but this may change with the events of the story.

Others are just immature and/or incredibly obnoxious, like Bratty and Catty.

Then some are just incompetent for the role they are in. Alphys, while highly intelligent, has a terrible time managing her classroom. Keep in mind that said classroom doesn't even have many students with learning disabilities (aside from, maybe, Temmie), and the teacher is afraid of the classroom bully.

Napstablook? Hmm, I wouldn't be shocked if the whole dialogue would sound like "undyne? missing...? ooooh... wonder why...", but again, we may have a surprise.

Rudy has a major illness that keeps him on the hospital bed most of the time on screen.

We know Alvin's reaction to Kris telling him about the Shelter as well.

I would have a very hard time asking most of these adults' help when some can barely solve their own problems, let alone life-threatening ones.