Impact of abandoned green card application for parents

[english_august]

Hello - I am a US citizen and applied for green card with concurrent filing of I-485 for my mother in December 2021. She came here in November 2021 on B1/B2. We expected that her GC would come quickly because of the immediate family categorization. We have now been waiting for her green card for almost 9 months now and she needs to go back for medical reasons. We even applied for Advanced Parole a few weeks back but it seems like even AP is taking multiple months. At this point, it seems like she will need to go back without any approvals which effectively means abandonment of her application.
What are the implications of this on her B1/B2 visa? We don't expect to again apply for her GC but will her B1/B2 visa will remain valid for a future visit?

[Dx134]

It isn't clear to me whether your mom still intends to go through with the AOS; based on the fact that she applied for AP, I'd guess the answer is "yes". Is she eligible for emergency advance parole? If you haven't considered it, that's something you might want to look into. (Or does even an emergency AP take months these days?!)
As for your specific question, I heard from others here that nonimmigrant visas are always voided by the IO at the interview when getting an immigrant visa through consular processing. As far as I know, this doesn't apply to the AOS process (while it is pending, that is...); people reenter with their H or L visas all the time while their AOS is pending. I don't know of any rule that states that B visas are an exception, but, you know, IANAL. If her visa indeed remains valid, I don't see any obstacles beyond proving to the CBP officer at the port of entry that she doesn't have immigrant intent.

[newacct]

I believe that their visas have been automatically voided by INA 222(g) due to them staying past the date on their I-94. See 9 FAM 302.1-9(B)(1). Although there is an exception for pending Extension of Stay or Change of Status, there is no mention of pending Adjustment of Status.