US Immigration from Vietnam

My mom is 60 years old, 10 yeard green card, has a house in the US under her name, bank account, filed tax.

She left US on November 2019, and stuck in Vietnam due to Corona. Right now she doesnt want to go back to the US due to surging of corona cases.

If she stay out of the US more than a year, wait until the corona vaccine develop and come back to the US, if the CBP let her in but request her to face immigrant judge, how long is that wait?

I know that she could apply for SB-1 visa, but its 50/50 chance, and she doesnt want to take that chance.

If she just go with green card without SB-1 Visa, she still has 70% chance of getting in.

1. You enter without being questioned - Good
2. You are questioned, but let in with a lecture - Good
3. You are questioned and paroled in to go and face an immigration judge who determines you have not abandoned status - Good
4. You are questioned and paroled in to go and face an immigration judge who determines you have abandoned status and deports you. - Bad

Thanks guy