Start with the recorded deed: it shows whose names appear as owners. California generally treats property acquired during marriage by someone domiciled in the state as community property, unless an exception applies.
That general rule does not settle who can sign for a particular house. How it was acquired, the deed, a divorce judgment or agreement, and any court order about the property can affect the sale. The title company reviews the documents to confirm the signatures and closing papers needed; a California family-law attorney can explain what an agreement or order means for you.
You can talk with us about the house while those documents are being reviewed. A conversation or offer does not change a court order.