You need to show that you can support your own family and your mother in order to sponsor her. If your husband co-signs, you can count his income too. You can see the LICO table at http://www.cic.gc.ca/English/information/applications/guides/5196E10.asp With yourself, husband, 2 kids and mom, you have to support 5 people so you have to be making a combined $46,850 per year.
However, sponsoring mom is not going to happen fast. Currently it takes 45 months to approve you as a sponsor, see http://www.cic.gc.ca/english/information/times/perm-fc.asp and after that, it goes to her home country, you can see processing times here: http://www.cic.gc.ca/english/information/times/perm/fc-parents.asp