This is definitely a scam. DO NOT give them any personal information and definitely NO MONEY.
Real grants do not require that you pay any money to receive your grant. If you are applying for legitimate grants the application information will tell you what it takes to be eligible and will also indicate how you will be notified if the grant is awarded. Typically this happens online and comes from the grantor.
It sounds like you are probably not dealing with an actual grantor but rather some service that claims to help you get grants -- for a fee. This is not the way real grants are applied for or won. Take a look at this article about types of grants and where to find them to get some real information. And remember, you never have to pay for a grant, do not give these people any money!