I believe this is precisely what the groups feature does. Create a group, apply the correct customers to that group and only those customers will be able to see whatever you mark as for that group only. You can do a lot of cool things like price reductions only for people in a certain group, only certain people can see certain categories etc.
This should give you a proper explaination.
http://doc.prestashop.com/display/PS15/Managing+Customers#ManagingCustomers-Groups