Amending tax return to include newly us citizen wife.

Hi, 

I am a fairly new Accountant who specializes in taxes. This is my first instance of this situation. I have a client who was raised in USA but left at some point to live in a new country. He met his wife there and they moved to the USA in 2021. She just received her social security card this year. The husband filled single in 2022 and wants to amend the return to show MFJ now that he has her SSN. Is that possible or can he claim his wife as a dependent to file Head of Household?