I am purchasing a home in California and have a loan just in my name. I want my wife on the title but the escrow company says it cannot be done. We must close close first and add her later.
Will this be expensive?

It shouldn't cost that much. There is a sticky post at the top of the Real Estate Law forum that explains how to do it. You can read it at https://www.askmehelpdesk.com/real-estate-law/how-add-someone-your-deed-91136.html