I pray that not only he will gain wisdom from the Lord, but for you too. May this teach you to not trust people with money even if they are from church. I've seen in my life this happening to too many people who think everyone that goes to church are honest people, but they are not. Second you should had never have gone lending money that didn't even belong to you, but your mother's.
Lord you see this situation this person is going through, have your perfect will be done to both parties. My this person's mother soon have her money back. May this person learn to trust only you. I pray in Jesus name amen.