The hospital is liable if--but only if--they were at fault. From what you write, they may not have been at fault...for example, if there was no restriction on your grandmother getting out of bed--and she did not need any restrictions--then her falling is not the hospital's fault unless they had left spilled liquid or something on the floor making it slippery. Or even if there were restrictions, if your grandmother ignored them (e.g. she was supposed to ask a nurse to help her get of bed, but decided to it herself despite the medical advice), the hospital would also not be fault. Only if you can show that the hospital either deliberately or careless did something wrong, would they be liable; the mere fact your grandmother was injured while in the hospital, without more, does not establish liability.