Dear ICQ1980:
LA Immigration will send your mom a letter very soon. They will tell your mother if she needs an terview or not. But most like, your mother will be interviewed. After interview, she might get a stamp at once or send a letter back to NSC back. My firends all asked lawyers to go with them. Immigration needs to confirm something in the interview. Till now all my friends are OK. So, you no need worry too much.