I can understand this is a frustrating situation for you. Who exactly is coming to take your grandmother to the bank? ... and to sign what papers exactly? Also... can you post some additional information about who "they" are as far as grandma not wanting "them" invovled, etc.
If grandma is behind in the rent, the landlord can legally evict her. You can learn more about eviction here:
http://resources.lawinfo.com/Search....:Massachusetts.