Do we need to wait till divorce is final before applying for Medicaid?

Did the lawyer who is handling the divorce understand the situation fully? Drastic actions that are going to impact Medicaid eligibility really need to involve an attorney specializing in Elder Law. It is a little late, but I suggest you consult one now.

Of course, if she is divorced she loses her community spousal rights and since they were married such a short time, she won't get his social security either.

OK, she gets to stay in the small home as the community spouse. But she can't sell it, because Medicaid will own his half.
Medicaid laughs at pre-nuptials. The way you have planned this she will walk away with all the assets and you will have Dad to care for, because Medicaid won't kick in.

They did a prenuptial even though they don't have a lot of money but they do both own a small home.

They don't have to buy anything together. Once they are married property and debts become joint. Let's say they have stock that has gone up since the marriage. The increase in value gets divided. Same for real estate.
If the increase in value is not equitably divided, Medicaid will reject the application or impose a penalty amount.

Within that year they didn't buy anything together.

I agree with Pam. Attempting to hide assets by divorce will not work. Medicaid will do a five year look back from the date of application on both their assets.

Angel

The wife is in for a rude surprise. Medicaid does a five year look back and will not recognize a one-sided divorce action aimed at preserving assets. They are not new at this.