I wouldn’t say “definitely”. In the 1870s, there’d still be a fair amount of unregistered births and she may fall into that category.
Irishgenealogy.ie has a transcription of the marriage (it has Tralee parish records to 1900) but doesn’t include the mothers’ names. This probably means they were not recorded but I think it is worth your while contacting the parish to be sure.
If you have not tried it already, you could look at identifying siblings for her – a birth or a marriage for one of them might give the mother’s name.