Thanks very much for commenting. I knew that I couldn't let her cry it out.
My mum still feels incredibly guilty for letting my older brother (her first born) cry. She didn't want to, but her mother told her that she had to leave him and wouldn't let my mum go to him. My grandmother thought she was doing it right.
There's just so much information out there that it's hard to know what's right. Going with what feels right to me is how I'm getting through this! I'm a first time mum so I have a lot to learn!