CAN'T FIGURE OUT APPLE ID AND MUST TRACK PHONE!

So, my mother just lost her phone about an hour ago. I went to track it using Find My Phone but she doesn't remember any of the informaiton 😠😐. I called Apple to figure out any options and they said one email address I gave her is CONNECTED to the apple ID but not the ID. She said there's nothing she could do. I used the "FORGOT APPLE ID" option but when I put my mother's first, last name, and the email address the woman said was connected nothing happened. I don't understand. I feel really bad and I'm just trying to help my mom (Although it's her fault for being careless with the phone and NOT remembering the information she uses) ANYWAY if anyone has advice on what to do, although I'm sure by tomorrow morning it'll be too late, that'll be great. Thanks in advance.