You must keep talking to your Gran! And you must pray for her even more so! She is in great danger! I'm sure she will have the JW Bible, the New World Translation. Ask her to open it to Galatians chapter 1 where from verse 6 the apostle Paul warns the Christians in Galatia:
"I marvel that you are being so quickly removed from the One who called you with Christ's undeserved kindness over to another sort of good news. But it is not another; only there are certain ones who are causing you trouble and wanting to pervert the good news about the Christ. However, even if we or an angel out of heaven were to declare to you as good news something beyond what we declared to you as good news, let him be accursed."
Now, put this question to her: "Gran, what is the good news, according to the JWs?"
But don't allow your Gran to show you the answer as written in any JW publications. Refuse to look at them. Insist that the two of you stick only to what the Bible says. If she has studied for a year she will certainly know the JW version of the good news (or, gospel.)
She will go on about the evil in the world reaching a climax when God will start His battle of Armageddon; that JWs will survive because they have pleased God by being the only ones in all the Earth preaching the good news; that the millennium will then start and Earth will become a paradise; no more sin, dying or tears; the resurrection of the dead will begin and take a long time to complete. All who come back as perfect humans will learn from the Armageddon survivors how to please Jehovah by following His instructions, that come from heaven via JW leaders on Earth. If they do the right things and remain obedient to Jehovah's earthly organization, they should then pass the final test at the end of the thousand years, when Satan will be released for a final attack. If they pass that test, they can relax. They will be finally saved and live forever on a paradise Earth. But if they disobey thereafter, they will be annihilated.
That is the JW version of the good news. Now. Get your Bible and study these passages:
Mark 1:15 & 6:6-13
Luke 5:32 & 24:45-49
Acts 1:8 & 4:10-12 & 8:35 & 10:34-43 & 9:20 & 13:38 & 17:18 & 18:25 & 28:31
Romans 1:1-9 & 4:23 to 5:9 & 6:22-23 & 8:1-17 & 10:9-17
1st Corinthians 1:23 & 2:2 & 15:1-8
2nd Corinthians 2:12-14 & 4:4-6 & 5:18-21
Ephesians 1:3-22
Philippians 1:15-18 & 27-29 & 3:9, 18
Colossians 1:19-23 & 2:2-3 & 4:3
2nd Timothy 1:8-12 & 2:8
Hebrews 6:1-3
1st Peter 3:18
Once you have absorbed all of those scriptures, you will see clearly what the biblical good news is. It does not include anything about what the JWs say is the good news! That's because, although God may do this, that or the other in the future, the good news is not about the future. It's about what God did, in Christ, in history, at Calvary and the empty tomb! It's not about earthly pleasures, it's about having our sins pardoned as an act of God's grace and love, and not due to anything we can do! The good news is all about Jesus Christ and realising just who He is and putting all our faith in Him alone!
If you don't have a clear grasp of that, the JWs will mold you like putty into becoming a JW, as they are doing with your Gran. But Galatians 1 warns us that if we follow those who preach another gospel - a gospel different to the one the apostles preached in the first century - we are accursed by God! That is why you must never allow their literature to influence you! It's based on a false gospel and a false Christ! Stick ONLY to the Bible and insist that your Gran does the same! If she's not prepared to do that, you cannot agree to let the JWs talk to you, or to view their literature. Please stick only to what the Bible says. You will be lost, otherwise.