Who can help my grandma make decisions while my grandpa is in skilled rehab?

Is there a family advocate or a resource person who can help my grandma navigate things while her husband is in rehab? We have concerns about his ability to obey orders upon release, questions about guardianship and her rights as a spouse, and possibly legal advice too. Is there someone who can act as a family advocate or facilitator in this case when my grandpa might not be able to make the best decisions regarding his care?