Bringing mother-in-law into US through sponsorship or otherw

I am trying to research this for my friend who is in a strange situation.

My friend is a US citizen and marrying a Canadian guy. Now she could sponsor him to come to US, but the problem is that his mother is dependent upon him, and he cares too much to just leave her in Canada.

So far the research she and I have done has not yielded any optimistic results about him being able to come to US with his mother. I don't think my friend can directly sponsor her mother-in-law, and he could only sponsor his mother after he becomes a US citizen. I have read that if he sponsors his mother after only getting a green card then it takes unnecessarily long. Way longer than if he were a citizen.

I do know that his mother can come and live with them for 6 months on tourist visa and then extend it by another 6 months, but they usually don't extend it beyond that.

Is there any way that he could bring his mother with him when his wife sponsors him so that the mother can live with them?

Thank you in advance.

The mother will need to LIVE in Canada (and vist for only six monthsper calendar year) until he become a US citizen (3 years). Only then will he be able to file a viable petion to have her move.

She should not overstay the 6 months as this will jeopardize her Provincial health coverage.

Note, too that even after her move to US, she will not be covered, or will have very high insurance costs.