I wonder. Let's assume for a minute that Ron was concerned about the security of the kids (I am saying "security" because I mean having an adult in the house, doors locked, etc.) Misty has just been on a binge. She was involved with some unsavory people in the use of drugs. And it is worth considering that Misty and/or Ron were likely involved in drug sales at one level or another, adding another layer to the contacts with unsavory people.
He may also have known that Misty didn't want to babysit and of course he knew that she had just gone off on a bender that weekend. So he's frantic, not just because he can't contact Misty, but that if she's not answering, she could either be gone or there might have been people allowed into the house that could have hurt the kids. I can't quite square up the frantic calls with stopping for beer on the way home. Hmmm.