Iphone 6 - iCloud ID is locked

My mum is using my iPhone 6 and she has used her own Apple id which is iCloud mail.

Now, don't know what reason. Her iCloud id being locked for security reason and she has tried to click "forgot id password" to reset the password but the funny thing is the reset email will be sent to her iCloud mail.

So, since her iCloud email is locked and she unable to sign in the iCloud email, how she get the reset email?

P/S: Apple didn't showing the security option as she has failed to answer the security answer.