Moles don't eat Hosta, voles do. The only way to find out if it's voles is to dig one up and take a look at the roots and crown or what is left of it.

Others have lost Hosta, but not on that scale. Post a pic of the roots of one if you can.

Steve

Well, it was an incredibly dry fall here.
If you weren't supplementally watering before the hostas went dormant, they could have died from the drying winds.
Couple that with the wet spring we've had.... I had hostas that were completely underwater.... that can cause crown rot.
I live in Lakeville, and I have already seen montana coming up, even in deep shade. Kabitan and September Sun are also up.
I suggest you dig up what you've got. If the roots are mush, it's rot. If they're dry and brittle, it's lack of water last fall. If they're non existant, it's a critter.

Another thought.... might they have been hit by some weed killer?

What a heartbreak -- when they are that old you think they're invincible. Hope you solve the mystery.
Jan

Thanks for the follow up everyone! There are a couple things I can definitely rule out:
Weedkiller (I have a dog with cancer so don't use chemicals)
Water: Watered heavily last fall
I have 1 of the 3 Montanas that is fine (they were planted together
Kabitan; Little bits here & there
So I will dig the one area that I had the greatest loss and see if I can "see" what is happening.
A couple years ago I had a vole (not a mole like I incorrectly mentioned) and he ate my "Fried Green Tomatoes" hosta
PS. My Salutes, Frances Williams, Crossa Regals, Striptease (I am a hosta freak), Elvis Lives, Sum & Substance and all the 25+ others are doing great. Some seem a little thin and that could be the dry fall/winter. But all the ones I lost were in a good amount of shade, even after the leaves went down.
I am thinking to that since I can't use chemicals, my yard is probably a haven for underground critters!
Fortunately for me, we have a red tail hawk and a couple eagles (along with a red fox) that have taken out every rabbit in the area :)
I will let you know what I find when I dig (or don't find!) & thanks!