response when a loved one tell you they want to die.

I has recently been helping my Aunt during the day taking care of my grandma who is 84. In the last year she has has 2 strokes and 3 seizures. She cannot communicate at all and now all she wants to do is sleep and has told us that she just wants to die. I have been trying to comfort her but now she is refusing to eat, take her medications. I hate seeing her like this because I know she is giving up. My Grandpa passed away in 2009 and they were married for more than 50 years. Any advice on how to ease the frustration? I don't want to her to die of course but there has to be a way to tell her that's it's okay.