I received a call from this number at my moms place n told me to call it back when I did a lady answer n told me that I have a warrant out for my arrest for not paying back a cash advance. Is this a scam number

Based on the fact that they claimed you would be arrested (a lie, you cannot be arrested for failing to pay back a loan) they are at the least violating Federal law. Since they are already doing that, there is a strong possibility they are trying to scam you and even if you do owe for a cash advance, paying them would not result in the cash advance being repaid since they may not have a legal right to collect. If you do have an unpaid cash advance, contact the original lender to see who they turned your account over to. Deal only with the original lender or the company they tell you is now handling your account.

You can't be arrested for debt so the warrant business is definitely a lie.  If you actually own such a debt then it's probably a bottom feeding debt collector.  It is illegal for them to threaten arrest so that alone makes them suspicious.  If you don't own such a debt I'd block the number and ignore them.  Here is the FTC site that explains your rights as well as what a debt collector can and cannot do.

http://www.consumer.ftc.gov/articles/0149-debt-collection

She said that it was for 500.00

She also said that the cops would be picking me up in 40 to 48 hours