Depends on the state. In Texas, for example, he can’t be recognized as a woman, period, and will be considered a man legally married to a woman, as before. In California, both 1 and 2, if carried out in deliberate legal fashion (and assuming the “presenting” is more than clothes and a name change), will result in your acquaintance being recognized as a woman, but I think the marriage would be annulled under current law.
I have a hard time imagining that the marriage will survive, though I wish them all the best. There are plenty of happily married cross-dressers out there, but the actual sex change might be just too much to ask of a spouse. But it is also possible that your friend might have been in an essentially sexless relationship and they’ll go on like before.
I’ll try to find the citations when I get home (and there are almost none, really) but IIRC a very large number of marriages fail as a result of one partner coming out as transgendered or transsexual, and even in the cases where the other partner stays through the transition, the 5-year survival rate for the marriage is bleak. I’m recalling a 90-95% failure rate within 5 years, but don’t quote me on that as I do not have a citation to give you. Now as for the case where the marriage happens after the transition or the coming out, those success rates are much more positive, because after all the other partner has entered the relationship knowing what they’re getting into.
IIRC as well, it was the other partner’s family and friends which were most influential on the success or failure of the marriage. And I reckon that has a significant impact on any marriage, really.