"I'll be back - with food and water." It'll be a simple matter to go out and find some deer or other Wilds animal for them to eat. Food at the Cafe would do for him, but not the spiders. He'll need to hunt.

He means it, too. He can't stay with the spiders forever, but he'll make sure they're safe until their mother comes back.

And if she knows Ben protected and fed her children, he'd hopefully look like a friend and not prey.