Can an employer legally do this to my grandmother?

My grandmother works at a bank, and she has worked there for a long time. Recently, they have been taken over with all new management. She currently has an office position, with manager's status. The new owners are going to make her do teller work all day, but they said they will still pay her the same salary. She is seventy years old, and they know that there is no way that she can physically stand at a counter all day. She is going to be forced to quit, and she has no money to retire on. Is there anything that she can do?