We understand that you're going through a challenging situation with your brother's mental health declining after the passing of your loved one. We commend you for your faithfulness in praying daily and seeking the Lord Jesus Christ for help. It's important to remember that our help comes from the name of the Lord, who made heaven and earth. As it is only by the name of Jesus Christ that we have access to God the Father.
In times like these, we should remember the words of the Apostle Paul. In Philippians 4:6-7 WEB it is written "In nothing be anxious, but in everything, by prayer and petition with thanksgiving, let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your thoughts in Christ Jesus."
The situation is undoubtedly tough, but we must also consider that God can use this trial to strengthen your sister's faith as well as yours. It's encouraging to see that you both are leaning on Jesus Christ, the true source of our help. This is why we are here praying together.
We must remember that our battles are not merely physical but spiritual as well. In Ephesians 6 WEB, it is written, "For our wrestling is not against flesh and blood, but against the principalities, against the powers, against the world's rulers of the darkness of this age, and against the spiritual forces of wickedness in the heavenly places." God is faithful to provide us with the spiritual armor we need to stand against such attacks.
Let us pray together:
Dear Heavenly Father,
We come before You in the name of Jesus Christ, lifting up our brother who is struggling with mental health issues. We pray for Your healing touch upon his mind and body. We ask that You grant him peace that surpasses all understanding, and that You guide him to professional help if needed.
Lord, we also pray for our sister who is bearing the brunt of these attacks. Please grant her the strength, patience, and wisdom to handle this situation. Help her to set appropriate boundaries for her own well-being and to seek support when needed.
Father God, Your Word tells us that nothing is impossible for You. We believe that You can turn this situation around for good, bringing healing and restoration to our family. If it is Your will, please intervene and help our family find a suitable solution, whether it be healing, a change in living arrangements, or the right help from professionals. We ask this in Jesus Christ.
In Jesus' name, we pray. Amen.
Please continue to pray fervently and consider fasting for this situation. We encourage both of you to seek support from your local church or Christian community.
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. 
