[morpheuskafka]

If she is no longer residing in the US, the legal thing is to enter as a visitor. There are two problems with this, first they will require her to sign a form giving up the green card status, and two, they may be suspicious that she actually intends to be a visitor since she is married to a US citizen.

They are definitely not going to let you extend the permit after it expired especially since you don't really meet the criteria for it (temporary long duration absence).

If you entered before it expires, you probably wouldn't face questions from CBP since you did get the permit, but that is just my guess.

[Taniwha]

She may find herself in the position I was in after 20 years we left the US, I stopped using my green card for entering the US because I was no longer a resident, but didn't realise I was required to physically hand it in when I was done with it (it was 20 years later) - got stopped at the border and got a good talking to. So make sure you hand it in when you're done with it