My child's surname has changed and he has a new passport, but the B2 visa has his old surname. Can we travel with the two passports and the documents that show his surname change?
According to the State Department here:
I changed my name. Is my U.S. visa with my old name still valid?
If your name has legally changed through marriage, divorce, or a court ordered name change, you will need to obtain a new passport. Once you have a new passport, the Department of State recommends that you apply for a new U.S. visa to make it easier for you to travel to and from the United States.
So it's possible, but going through immigration may take extra time as they review the documents.