The FTC warns about the family emergency scam here http://www.ftc.gov/bcp/edu/pubs/consumer/alerts/alt111.pdf  
Report to the Internet Crime Complaint Center http://www.ic3.gov/complaint/default.aspx , the Federal Communications Commission http://esupport.fcc.gov/complaints.htm , the Federal Trade Commission https://www.ftccomplaintassistant.gov/ and your state AG http://www.naag.org/current-attorneys-general.php as appropriate.

My mom receive a call saying it was her nephew asking for money and to be sent to Mexico...

I also got a call in mexico from this number, pretending to be my cousing.

This number called and claimed to be my nephew and asked for money. Don't answer these calls they'll mak you send them money & you'll get robbed.