I have a number of hostas... far fewer than I started out with:
coffee grounds- unless very dry and continuously refreshed (dry!) not much of a deterrent
crushed egg shell/ gritty stuff- plants seem to disappear from within... slugs unlike snails, can live underground and surface within a protective ring!
pellets! you can get organically certified, so they'll kill the slugs and snails and not anything that subsequently eats them. I have come to the conclusion that this is the only effective defense.
I haven't yet tried nematodes, but am considering. I have recently started using a garlic spray/ wash to deter as I have several large shrubs that snails seem to launch themselves onto from all manner of other launchpads/ amble onto from nearby or overhanging plants, so pellets on ground not much use. Have yet to determine the effectiveness of this.
Having spoken to a specialist Hosta grower at one of the flower shows (yes... I was the 50 millionth person to ask..), judicious use of pellets and garlic wash are the answer!