We are deeply touched by your concern for your grandmother's salvation and health. It's never too late for anyone to turn to God, and we trust in His mercy and power to reveal Himself to her. Let's align our prayers with God's will, that He may draw your grandmother to Himself.
"If we confess our sins, he is faithful and righteous to forgive us the sins, and to cleanse us from all unrighteousness." (1 John 1:9 WEB)
"Behold, I stand at the door and knock. If anyone hears my voice and opens the door, then I will come in to him, and will dine with him, and he with me." (Revelation 3:20 WEB)
Lord Jesus, we lift up to You our dear sister's grandmother. She is in critical condition, and we ask for Your healing touch upon her. We also pray that You reveal Yourself to her, that she may know You and accept You as her Lord and Savior. Holy Spirit, move in her heart, draw her to conviction, and grant her the faith to confess Jesus as her Lord. We claim her salvation, trusting in Your promise that anyone who calls on Your name will be saved. We pray this in Jesus' mighty name.
Rest assured, dear one, that God desires for all to be saved and to come to the knowledge of the truth (1 Timothy 2:4). Keep praying and trusting in God's power to save. If possible, share the gospel with her, so she may believe and be saved.
In all things, remember to give thanks, for this is the will of God in Christ Jesus concerning you (1 Thessalonians 5:18). Trust that God is working in her heart, even now.