Oh wow. Your wife is going to have to prove she hasn't abandoned her residency, which is normally automatic with a 2+ year absence (or even 1+ year without a re-entry permit). This will come down to establishing existing ties to the United States. Married to a US citizen helps but this doesn't mean you can stay abroad indefinitely either.

I hope she was filing US taxes while abroad. Every US citizen and LPR has to do this. Not doing so is more evidence of residency abandonment.

An obvious exception here is if you were sent internationally to work for your US employer on what is essentially a temporary assignment eg working for a US consulate in another country.

You have the option of just returning to the US before her green card expires. This will probably land her case in immigration court and you will need a laywer. Or you apply for re-entry at an embassy. You will also need a lawyer.

Get a lawyer.

If you do return and then leave again in relatively short order, you can probably kiss that green card goodbye, particularly if it's before your immigration court date. USCIS takes the view that green cards are for people who reside in the United States. The only form of "return when I want" status is citizenship.