If it was me - I think I would put my relative on the plane with a letter to CBP that she can print at her origin stating the intention of her visit to the USA, addressing the fact that she speaks no English, and providing contact details to reach you for confirmation of the message.

Have a copy of her passport / visa / return flight information handy and ready to confirm information they may ask you.

It would be good to advise her language preference in the letter, in case they need to find a translator for some reason.

You can request wheelchair assistance - which will be helpful.