My wife (US citizen) and me are scheduled for an AOS interview next week. I believe the first thing they ask us is for our state IDs, is that true? She cannot find her's .. would that be a problem, and are there any alternatives. What would be a good reason to give - or should she say she lost it, and would that be well accepted.

Why doesn't your wife just go to the DMV and get a replacement driver license or ID? Unless there is something underhanded or illegal, this is the logical thing to do.

Otherwise, the situation looks very suspicious.

The earliest appointment we can get is after our interview, and it takes upto another 60 days to get the card.

use the passport as ID

I live in Arizona. When I moved recently and updated my address with the DMV on their website, I received a new license in the mail within a week.

Had I gone to a DMV office, I would have gotten a new license immediately.

Hi!
When we had our AOS interview (Atlanta), I showed my EAD card (I also carried my passport). The EAD card was accepted as valid identification. We also showed our interview notice.