The reason she was asking for the test was because there was a lot of circumstantial evidence that suggested the body might be that of her mother.
1) Her mother was missing.
2) The body was the same height and build as her mother.
3) The police artist's sketch bore a striking resemblance to her mother.
4) The woman in the river was wearing a necklace that was identical to one that her mother owned.
The reason the police refused to do a DNA test is that there had been unconfirmed reports that somebody somewhere had allegedly seen this woman's mother alive after they had pulled the body from the river. They finally relented and did a test after the woman went to the CBC with her story. The CBC pointed out that after three years, there had been no further sightings of the woman's mother, and they had still not managed to identify the body. The DNA test revealed that the body from the river was... her late mother.
I don't know who writes their news copy, but they concluded the story with, "The police refused to do the DNA test because they were sure that her mother was just missing and they were convinced that she would eventually resurface..."
I have no words.