Have to disagree.
Yes, Ted’s BC showed a US born women (we assume) as his mother.
That woman followed husband one to England, where she worked (?) and gained British Subject status (?).
That woman followed husband two to Canada, where she worked (?) and gained Canada Citizenship status (?)
Finally, did Ted’s Mom ever renounce her American Citizenship while pursuing a new life in two different Countries?
That said, Ted needs two US Citizen parents, and to be born in the US, to be Natural Born US Citizen
All the other stuff, mom's US residency, possible taking of Candian citizenship in particular, go to finding citizenship. But we don't have to find citizenship to exclude him from NBC.