She can apply from Mexico to enter legally, and her hubby can be her sponsor as a new immigrant. Pardon me if I don’t take out my violin.
She can apply but, her chances of gaining entry are at exactly zero right now.
If she wants to apply, agree to a fine and probation, as well become a legal resident with stipulations then maybe that would be fine.
I believe that her husband is illegal too. She’s within walking distance of her family. They can go and be with her quite easily but then papa can’t come back to the US and they lose all those bennies.