his residency is only going to matter if you sell after marriage. then the exclusion could be as much as $500,000
sell before and only you get it and its a max of $250,000
as for proving he occupied it for two years if sold after marriage and you need more than the $250,000 exclusion ask then because the laws change and it's really a question of what will satisfy an IRS auditor if they even ask and that's if you get audited. no proof needs to be submitted with the return.
