Spell out the number for a person’s age; don’t use numerals.
Hyphenate the number and year and old when these are all used together as a single adjective: His one-hundred-twenty-year-old grandmother is one hundred twenty years old.
Do not capitalize the first word of a dialogue tag following the dialogue.
Deathbed is one word, not two.
You’re the last grandchild to talk privately with your one-hundred-twenty-year-old grandmother on her deathbed.
“Do you want the good news or the bad news?” she asks, knowing she will have only enough time to explain one secret or the other.
There’s a viewpoint glitch in these two paragraphs, but I don’t feel like rewriting the whole thing to fix that… If you are the POV character, how do you know what the other character, the grandmother, knows about how much time she has? This, friends, is what is meant by the term head hopping — at least what sensible people mean by that term. There are idjits who call it head hopping if a novel has one viewpoint character in one scene and someone else in the next, but they’re wrong. Also, as many writers of science fiction, fantasy, and paranormal romance know, a POV character who can read minds/sense emotions makes the rules about “head hopping” a lot more flexible. 🙂