Kindly assist me with a bandwidth monitoring tool that i can use to view usage per pc. I do not have a proxy servers users connect direct to a cisco 1941 router.
You may have an option to enable NetFlow on that router. More info here
Once enabled you need to use a tool like SolarWinds NTA which can take this NetFlow data and show you what data is associated with what PC. Note that this will only show usage at the edge (Internet) but looking at your question I think this is what you are looking for. If you want to also see bandwidth figures for inside the network there are also other options.
Hope this helps,