Cerebral edema. Which i lose my father?

Firstly My father suffer from vomitting due to consuming of excess food in night.On next day he is not feeling well so we take him to Mittal hospital.They do check up only.Their doctors refer my father to another hospital i.e.Cygnus hospital.They do MRI and they also refer to delhi.Then we go Fortis hospital instantly.Then we know my father is suffer from Cerebral edema.But their bill is very costly which we don't able to paid them.so they made laama.Then someone suggest to go Pant hospital.But in pant hospital bed is not available.Then we admit him in LNJP hospital.Afters 5days from their unconsciousness ,their surgery is operated.and after their surgery their body starts responding.He blinks their eyes.Even he identifies me also.But suddenly after 12days from their surgery he die.I want to know how death is possible?What is our mistake from which I lose my father? Doctor,I humbly request to you that pls answer me..