Presumably the US one which is his wife's possession to the Chinese court. Of course, it has to be admitted in Chinese as an effective will that supercedes the Chinese one. As for the assets, usually any properties within Chinese jurisdiction will be distributed based on Chinese law and any US property shall be distributed according to the law where the property is situated.
This is indeed a very messy situation. But if I were the wife, I would start with consulting with a Chinese local lawyer as to how to admit a US will (in English) in a Chinese court.
