We understand your concern for your son and we are here to pray and provide biblical encouragement for you both. Firstly, it's important to remember that God has not given us a spirit of fear, but of power, love, and a sound mind. (2 Timothy 1:7 WEB)
Whenever we have concerns or fears, we should turn to God and cast all our anxiety on Him, because He cares for us. (1 Peter 5:7 WEB)
Let's pray together:
Dear Heavenly Father,
We come before You in the name of Jesus, lifting up our sister and her son. Lord, You know the struggles they are facing, and we ask that You heal her son's mind and replace any lies of the enemy with Your truth through the Holy Spirit. Help him to be respectful, kind, and considerate towards his mother and grandmother.
Lord, we also pray that his behavior will be peaceful and calm, not causing any disturbances or disruptions, especially in their living situation.
Father, we ask that You provide for all his needs, that no weapon formed against him will prosper, and that any evil will be turned away. We pray that You will give his mother wisdom, strength, and courage as she guides her son. Help them to trust in You and be filled with Your peace.
Please, by Jesus Christ, Amen.
In regards to the behavior and attitude you mentioned, we encourage you to teach your son to honor his mother and grandmother, as the Bible instructs.
Children, obey your parents in the Lord, for this is right. Honor your father and mother, which is the first commandment with promise, that it may be well with you, and you may live long on the earth. (Ephesians 6:1-3 WEB)
Also, remember that God corrects and disciplines those He loves.
For the Lord reproves him whom he loves, even as a father reproves the son in whom he delights. (Proverbs 3:12 WEB)
It is good to teach our children right from wrong and encourage good behavior. God's discipline is a sign of His love and care for us, and we should reflect this in our parenting.
Lastly, we did not see any mention of Jesus Christ in your prayer request. As Christians, it is only by the name of Jesus that we have access to God the Father.
Jesus said to him, I am the way, the truth, and the life. No one comes to the Father, except through me. (John 14:6)
Neither is there salvation in any other, for there is no other name under heaven, that is given among men, by which we must be saved! (Acts 4:12)