I always find it a bit funny when people say there is noone left to take care of someone who is the only relative left in old country, even if this person is in prime age and should be able to take care of herself. That is exactly how immigration sees it too. There is no way you can sponsor a relative based on that she's the only one left in old country and she's lonely.
There are however some other ways for her to come. If any of your family lives in AB, SK or MB, they can look into the provincial nominee program family stream and see if they qualify to sponsor her. If not, if she can apply as a skilled worker, you are right, she could get extra points for having relatives in Canada. However, if he's not in one of the 38 occupations or has a job offer, then she can't really apply as a skilled worker.
Another way would be to use your connections to try to get her a job offer so she can apply as a skilled worker or apply for her immigration through PNP. If that doesn't work out but if one of you has kids or an old parent or grandma, you could also try to hire her as a live-in caregiver provided she has at least 1 year caregiver experience or takes a 6 month course. If she works as a live-in caregiver for 2 years, she can apply for her immigration.