As am I. Having said that, given these nuns were most likely in communion with the Vatican II sect, I think the bigger concern is whether they died as a Catholic.
That would be on an individual basis. This dogmatic sedevacantist reference to Vatican II as a non-Catholic sect is misguided. Unlike most non-Catholic sects, which have overtly broken from the Catholic Church, with the Novus Ordo it is very possible for someone to be in material error only, while continuing to profess the Catholic faith. There are many souls who still have the faith in the Novus Ordo (certainly only a small percentage of the whole, but not a trivial number in terms of raw numbers). Many of them either came to believe that V2 could be understood as in harmony with Tradition if you apply some hermeneutic of continuity, but far more only vaguely understand the errors of Vatican II and what the controversy is all about.
It's interesting that a lot of dogmatic sedevacantists are among the biggest enemies of EENS dogma, holding that it's possible to be saved outside of the Church due to material error, and then make zero allowance for the possibility of material error in the Novus Ordo. And it is in fact in the Novus Ordo that such error is possible due to people believing that it's still the Catholic Church. That is in fact the very definition of material error, where you believe something because you mistakenly THINK it is taught by the Church. So even if you hold an error, it's not because you have the wrong formal motive.
So, at the end of the day, it's a case by case thing with each nun. Some probably had no supernatural faith due to heresy and modernism, while others very possibly kept the faith.