Well, I am 100% sure that SHE can apply for another EXTENSION, even if she is PAKISTANI CITIZEN....
But, Since she has been extending her TRV so many times, the LIKELIHOOD is that she may not be granted TRV as her ties to home
Country (PAKISTAN) seems to be weak (Note that STRONG ties, like job, taking care of child, grandchild, property docs etc, is the vital CONDITION to obtain a TRV Canada).
Everything about applying TRV can be found on website, Also she can apply ONLINE..
http://www.cic.gc.ca/english/e-services/mycic.asp
Extension is not the issue she has got her extension already its the trv she needs to come back to canada n she has been visitor for almost 5 yrs n she has never been rejected for trv either now i have chks the link alreasy thanks for the reply will chk again to figure it out
I hope you like the help