hi hon

just to say, i'm from kentucky, my mom still lives there : )

i feel really really bad for your grandmother. i know she does have other children, because you said, but , i am a mom. and i have two daughters. and if something happened to ONE of them, it still would never be healed.
my dad died at age 59, two years before my grandmother died. his mom was 90 when she died, and i think she would have lived longer but for the grieving over dad. it just took all the life, out of her.

all you can do, i think, is keep telling your grandmother you are there for her, all of you are there for her, surround her, if you can't be there physically then check in daily or 3, 4 times a week with a phone call. .
write letters, yes even snail mail.

and like someone commented prior, yes, have her see a doctor. she likely needs a bit of medical help.

grieving is hard physical, mental and emotional, work. and it takes time.

she is lucky to have someone as loving and caring, as yourself, around her.
i wish all of you the very best