OP- no single semester is going to change the trajectory of your life. So take the B, get a C, you will be the same person you’ve always been. If the class is messing with your mental health- drop it. If the class is going to prevent you from getting a good nights sleep- drop it. This is a great example of why doing things for the sake of college admissions (I assume that’s why you accelerated? Unless it’s just for the love of math) usually doesn’t pay out.
Take the classes you need to take in order to understand the material and cover the curriculum. If that means dropping down a level in math- do it. Or if the challenge feels manageable with some tutoring- then stick with it. But I wouldn’t let worries about college dictate what you do right now.