Sorry to hear of mil's illness. In the past airlines have given discounts to imed. family for last minute flights due to death or severe illness. You may contact the airlines directly to ask if they still do this.
You could try Travelocity.ca, and those type web sites, but if you see a fare you like, I'd check that airlines web site also. Sometimes- many times-the airline will have the same or cheaper fare. If that's the case, I prefer booking directly with the airline.
With West Jet- check both arriving at YVR and Abbotsford. One may be cheaper?
Best of luck.