Unfortunately I'm getting onto this thread a few days late, but hopefully this is still helpful.
The first thing you need to do is determine exactly how these items wound up on your husband's credit report. If it was truely a mistake (which does seem to happen frequently) and your son provided accurate info when he applied for the cards and loans and whatever, then you'll need to go to all three of the credit reporting agencies and work to get that information off of his report.
However, if this was not a mistake and your son provided your husband's SS number then you have a bit more of a problem. That was truely fraud and the good news is that it will probably be easier to get the fradulant accounts removed from his credit report, but the bad news is that the credit reporting agencies will only remove fradulant accounts if you have reported it to the police and you can provide them with a copy of the police report. Of course, reporting it to the police likely means that your son will be prosecuted for identity theft, but it's also the only way you can get fraudulant accounts removed from your husband's credit report. So you will need to decide if you want to take that path or not.
Unfortunately, neither of these options is likely to be terribly quick. You're probably looking at several months at best to get everything cleaned up. The first place to start is to get a copy of all three of your husband's credit reports. Once you have those in hand, figure out exactly which accounts are not your husbands so you know what you're up against.