get calls saying won money and a car but wants you to send 850$ by money gram or western union in order to get a reciept number and then they will deliver the prize, say they work for fedex but called fedex and they dont,

This is a scam, make sure your mother knows this and have her hang up or ignore their calls. Further DO NOT call back the number, it is not a toll free number. This is a long running scam from Jamaica were they try to scam people to wire money to them for "fees" for your winnings. You send the money, you never receive any winnings, you are out the money.
Further, their phone number may incur hefty fees when you call them. The 876 area code is for Jamaica and many scammers set up phone number that will charge you tens of dollars per minute or more plus sometimes a large connection fee.

Ignore/block the calls.

A caller from the above number has been calling my senior citizen mother soliciting funds to release a $500,000 check.  He told her she won the money in a lottery from a grocery store entry and the funds were from Super Rush Casino in Florida.   The caller also mentioned she'd won a new mercedes benz and the receipt necessary to release the winnings was being held at FedEx pending her payment of $800.00 in service and/or storage fees.   He called himself Jack Wilson but had a relatively strong accent.