[abcabc321321123]

Yes, that statute requires a warrant. However, the exclusionary rule is only applicable to one with a "reasonable expectation of privacy." In the hypothetical, C does not have such an expectation, and therefore C cannot challenge the admissibility of the evidence notwithstanding the statute.

[ewoodrich]

Yes, you are correct. Upon rereading your hypothetical, I realized I interpreted it incorrectly.

Of course, it doesn't mean that such evidence would be especially compelling to a judge or jury in those circumstances, but that's a separate matter.