For the boards call, is one of the boards in a sub-category beneath the category you have in your REST call? if so, you should do /boards/nested -- the nested call gets you not only the boards in the category you are are making the call for, but also for any sub-categories. If you are making the call without a category specified, the nested call gets you all boards in the community rather than just the boards that are created directly under the community node.
If you want all the boards for the category and any sub-categories: myurl.com/restapi/vc/categories/id/Prepaid/boards/nested
For the /blogs call, it should work, but again you might have your blogs under categories/sub-categories. The /blogs call is actually deprecated, so we don't have support for /blogs/nested. You want to make the /boards/style/blog/nested call instead -- here is the documenation for that call:
http://lithosphere.lithium.com/t5/rest-api/bd-p/developers-rest-api?leaf-id=Community.boards#Community.boards.style.style.nested