Would a durable general POA be sufficient enough for a loan closing? It looks like it is a general document, not prepared by an attorney or anything. The POA says the wife has power to enter into mortgage transactions on behalf of the husband buts its very general. Would we need something more specific that details the actual transaction?

Validity of a POA is determined under State law. Any questions regarding the validity of a POA really needs to be directed to your legal counsel. In some States, you only have so many days to make that determination.