Taxes And Father That’s In A Coma

Good morning, (Based in Atlanta, GA area) My mom and I were talking last night about the upcoming tax season. My dad has done their taxes (jointly as a married couple) for the last 30ish years. Currently my dad is in a medically induced coma in the ICU (double pneumonia, liver disease, and I’m sure a few other conditions). Before they sedated him, he was very confused, not lucid, just overall not “there” mentally. Hopefully that made sense? Anyway, my mom is concerned about filing the taxes because she cannot sign for my dad. We are not sure how long he will be in a coma or if he will be coherent when he wakes up. My mom said she can figure out how to do the taxes and I plan on helping. But she wants to know what she needs to do on her end to file jointly and not sign my dad’s name, within legal terms. Thank you!