We understand your concern and heartache for your grandchildren and their parents. It is beautiful to see how much you love and care for them, and it is commendable that you spent quality time with them. We will stand with you in prayer, trusting that God is at work in their lives.
Let us remember that God has promised to make our efforts in teaching the Word to our children and grandchildren fruitful. As it is written in Isaiah 55:10-11 WEB, "For as the rain comes down and the snow from the sky, and doesn't return there, but waters the earth, and makes it bring forth and bud, and gives seed to the sower and bread to the eater; so shall my word be that goes forth out of my mouth: it shall not return to me void, but it shall accomplish that which I please, and it shall prosper in the thing I sent it to do."
We pray that your grandchildren will come to know Jesus Christ personally, and that He will draw them to Himself through the Holy Spirit as per John 6:44 WEB, "No one can come to me unless the Father who sent me draws him, and I will raise him up in the last day."
Also, we pray for your son and his wife, that God may open their hearts and turn them towards Him. As the Bible says in Acts 16:31 WEB, "They said, Believe in the Lord Jesus Christ, and you will be saved, you and your household." Remember that it is only in Jesus that we have access to God. There is no other way to be saved but by His name, as per Acts 4:12 WEB, "There is salvation in none other, for neither is there any other name under heaven, that is given among men, by which we must be saved!"
Regarding your grandson's allergies, we pray for God's healing and comfort. As per Psalm 103:2-3 WEB, "Bless Yahweh, my soul, Don't forget all his benefits, who forgives all your sins, who heals all your diseases."
We encourage you to continue being a godly influence in their lives, demonstrating the love of Christ, and praying fervently for them. Trust that God is faithful, and that He desires for all to come to the knowledge of truth. As it is written in 2 Peter 3:9 WEB, "The Lord is not slow concerning his promise, as some count slowness; but he is patient with us, not wishing that any should perish, but that all should come to repentance."
Join us in praying, "Father, in the precious name of Jesus, we bring these beloved grandchildren and their parents before You. We ask that Your Holy Spirit will draw them to You, and that they will come to know Jesus personally. We pray for their protection, for godly influences in their lives, and for healing from allergies. We trust in Your faithfulness and Your promises, Lord. Give the one who submitted this request the strength and wisdom to be a godly influence, and to pray without ceasing. In Jesus' name, we pray. Amen."
We are here with you, standing in the gap for your loved ones, trusting that God will answer our prayers according to His will. Be encouraged, and continue to demonstrate the love of Christ to them.
Prayer Focus: God, Thank You. Thank You for loving me. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
