legs11,
As JJ said, you really need some more names and some dates before you can try to find them in Canada.
It sounds like we are looking at an emigration that took place well into the 20th century, if Harry and Matilda were married in 1879. In order for the sister to have emigrated with a married daughter, we are looking, at the VERY least, at 1919 (if the sister was the first child of Harry and Matilda and then had Gladys at a young age herself). Do you have a more precise sense of the date? A birthdate for the sister would be a good clue.
And, from what I understand, we are not actually looking for someone named Price, since she would have a married name. So you need to use English BMD records to try and find which Price sister you are talking about, her married name (this would be the same as Gladys' maiden name, right?) and, ideally a married name for Gladys and her husband's full name. Perhaps someone on the Rootschat County Board for the area where they lived might be able to help you find all the pieces.
There are a few possible sources to try finding them in Canada. Once you have some names, please let us know and we will do our best to point you in the right direction.
Martha