谢谢答复。但我刚才查了USCIS的网站，上面说

Valid Passport-B1/B2 visa applicants must have passports valid for six months beyond their intended period of stay in the United States. If your passport will expire less than 6 months from the date you plan to leave the United States, or is damaged, or you do not have a page for a visa, please get a new passport before your interview.
如果是这样，是不是我妈应去换新护照呢？如果用新护照，她的B2VISA 在老护照上，怎么办？