If one of the grandparents were willing it might be a decent compromise, but I'd be suggesting that OH goes as well so he can get to know the other daycare parents. Or at least getting him to be more involved so he's more comfortable with this kind of thing. Because there will be plenty more of them over the years, believe me!

If it's in a few weeks you could otherwise have a playdate with a couple of the kids + parents so he's at least met them before and will have someone to talk to - I get that it's pretty daunting walking into a party at someone's place knowing absolutely no-one, as I've done it several times with DD