I'm now confused. Let me get it sorted out.
The money went through to your mother's account according to Maybank.
Your mother doesn't see the money.

So where is the money? If your mum doesn't have internet banking, can still check via ATM to see any money transferred out or not. If not, than where is the money as they already confirmed went through. If it was transferred out, than lodge a police report to give it to the bank to trace the transaction.