If You are married and your spouse dies, his son owes the IRS lots of money can they come after my husbands estate?

If your son is the beneficiary, and he owes, then yes, the money goes into his bank account, they take it.

It is his son and my spouse does not have a will is it divided between me and the children or does everything go to the wife after husbands death if he has no will?

This is not a marriage issue so I've moved this thread here.

If there was no will the estate is distributed according to the laws in your area. It could all go to you or it could be shared.

The IRS can attach his inheritance, but only his portion after the estate has been probated.

If there is no will, it will depend on the laws of that location, in the US , it will vary by state, in some states the wife will get everything, in some the children will get a share.

If there is a share going to that specific son, then his part can be attached