Hi Christopher,
Looking at the datasheet for the MRF24WB0MB it's my understanding that it does NOT contain the TCP/IP stack. On page 7 it says
The MRF24WB0MA/MRF24WB0MB modules are designed to be used with Microchip’s TCP/IP software stack.
The combination of the module and a PIC running the TCP/IP stack results in support for IEEE Standard802.11 and IP services.
So if I don't read that completely wrong you need to run a TCP/IP stack in the PIC you're using to drive the MRF24WB0MB. Alternatively you can pair it up with the MCW1001A which I suspect is just a PIC preprogrammed with Microchips TCP/IP stack and some user interface code. What you'll end up with would then be something like this.

You don't NEED to code in C to use MRF24WB0MB directly with a PIC but the free Microchip TCP/IP stack is written in C and to use THAT you'll need to write your application in C. Obviously you COULD develop your own TCP/IP stack in PBP but that is a monumental task and then some. Fred Eady (I think) has posted some TCP/IP code for PBP on this forum in the past but I have no idea what's implemented and in what state it is.

The RN-171 on the other hand does seem to have the TCP/IP stack already implemented within the module and if you look at the features you'll see
•Hardware interfaces: UART and SPI Slave
And in the datasheet it says
• Host data rates up to 921 Kbps TX, 500 Kbps RX for the UART, up to 2 Mbps over the SPI slave
Please note that I don't have any experience with either module. I do have a MRF24WB0MB + MCW1001A module but haven't done anything with it.

/Henrik.