Actually, I believe you missed mine, I was being humorous, but I see now that I've got to be blunt with you. All religious beliefs aside, you simply don't tell her. It is not your place.
Look, it's like when you have tell someone that their cough is actually being caused by a metastatic carcinoma. Some people firmly believe that they will be healed. And so what? Best case scenario, they die believing that God might still heal them. Worst case, they die in desperation believing that their God has abandoned them. By harping on the extreme hopelessness of their circumstances all you do is hasten their demise. For example, there was a famous study concerning the effects of hope on drowning rats. In this particular rat-drowning study, the rats that were pulled from their buckets just before drowning would swim for nearly twice as long as those allowed succumb to exhaustion and unconsciousness (there was a similar study done with puppies too). All telling her would do you do is tear away that little shred of hope from an old woman. Besides, I'm sure she does understand the gravity of the situation whether you're aware of it or not.
Simply put, there is no good in you telling her that she won't be healed. No more anyhow, than there is in my telling you how unattractive the woman in your avatar photo is. See, no matter how true the statement is, it is just unnecessary.