Canadian Born Mother- How do I obtain citizenship?

My Canadian born mother passed away in 1974 when I was 10 years old.She kept her citizenship active until she died.

My father is a U.S. citizen.

How would I go about obtaining citizenship?

Instructions are here:

http://www.cic.gc.ca/english/citizenship/proof-how.asp

You’ll need to include proof of your mother’s birth in Canada (e.g. birth certificate).