Hi What research have you already done?
Your Grandmother Agnes Margurite POWELL nee LePRETRE
daughter of Michelle LePRETRE and Pauline DEROSHAY or DUROCHER.
Registration of Death for your Grandmother might show the correct spelling of your grandmothers parents.including maiden name.
Death Registration for your GGrandmother Pauline - should show correct spelling of the maiden name.
Marriage of your Grandmother - will show her Maiden name and correct spelling of mother.
Perhaps family connected:
Local History Books: Families submitted family history/stories to a Local History Book Project in the late 1980's.
LePRETRE, Emil; Ten Dollars and a Dream; Northern Lights
LEPRETRE; Peace River Remembers; Peace
DESROSIERS, Charles; Turning the Pages of Time; East Peace
other spellings
DEROSIER;DEROCHIE;DEROSSIERS DES ROSIER, DES ROSSIER
DESROCHER