First test is whether she is a person, i.e. if she is alive.
The ultimate medical rule is brainwaves. If an EKG shows human-looking brainwaves, she is alive. If not, one can make a legal case that she is not a human, but a "zombie virus" tapping into her memories for its own gains.
If EKG results are a subset of normal human brainwaves, she is a living human, but a disabled one.
Lack of heartbeat or other biological reactions is not enough to declare a person dead if there are brainwaves.
If she is declared a living human being, getting her identity back is a matter of working the bureaucratic machine. False death declarations happen all the time. Here are couple
reads, sorry if 2nd one is paywalled.
Having her Photo ID and birth certificate would help a lot.
Having DNA samples of her old self (hair) would be even better.
Obviously, that will require cooperation of her ex-husband.
If it works, she can have half of the business back.
Marriage will likely be annulled, so she cannot have the husband back.
In any case, government will keep her quarantined and under study for quite some time, to see if she is contagious.
If she is not declared to be alive, she is "human remains", which will probably be released to her ex-husband. There are typically laws for safe disposal of remains, and they might really depend on specific country and even state/province within it.