I want to measure the bandwidth used by particular network or particular PC through router WAN interface. I guess we can use Netflow apart from this is there any other options to measure.
netflow is probably the best solution but it requires some effort
for getting simple data you can use ip accounting output-packets in interface configuration mode, and then sh ip accounting to see results.
There is no aggregation of data per specific source and you should do this in some way after having exported the show output
NBAR can be useful too.
Hope to help