Yes, Deschaines is a variation of Miville-dit-Deschenes.I am aware that her grandmother was Marie-Thecle Miville-dit-Deschenes.However, here is avery interesting note: After your grandmother Elmina died in 1902 Antoine married Marie-Alma Miville-dit-Deschenes in Ste-Anne-de-la-Pocatiere on 28 July 1903. Alma was a first cousin to my direct line paternal great-grandfather Ferdinand Deschenes.My great-great grandfather Firmin Deschenes was the last descendant to carry the Miville-dit-Deschenes name in my line. Alma used the Miville-dit-Deschenes name in her Marriage Register entry. The Beaulieu's carried the Hudon-dit-Beaulieu name. Many later dropped the Hudon part like many of my relatives dropped the Miville part of the "dit" name.
Your grandmother may have died in the Madawaska area of New Brunswick since she had many relatives there.However, her funeral and burial took place in the Parish of St-Pascal, Kamouraska, QC on 7 July 1902. I do speak and read French and I have read her St-Pascal Parish Sepulture Register entry.Many of her Plourde relatives lived in the Madawaska area of New Brunswick and in the St. John River Valley area of Northern Maine. There are about 18 parishes in the Madawaska area of New Brunswick.Many times they are listed with "-de-Madawaska" appended to the parish name such as St-Francois-de-Madwaska.On the US side of the St. John River only the town of Madawaska carries that name.My sister lives in Madawaska, Maine.