My husband took a day off work due to the fact I had a miscarriage. His employer asked for him to bring in my discharge papers from the hospital for proof. Can she do this? I feel it violates my rights.

They can ask for proof, I will assume he told them that is why he was taking off. You can block or white out the medical reason if you wish,

If many people take off work for medical reasons, the boss wants proof that was why they took off.

There's a merger of 2 kinds of rights here. An employer has a right to ask for proof of reason for taking a sick day, for example, or just a day off that doesn't fall under a category. (I presume he didn't take a vacation day.) Don't forget that those days off are a privilege, not a right. Even if he takes a day off without pay.
You have a right to your medical privacy, and don't need to copy sensitive papers - but if the employer wants proof of why he was out, then you need to provide it in a way that doesn't compromise other medical information. I'm sure that's why just the discharge page was asked for.

A discharge form isn't a copy of your medical records... all it says is you were in the hospital as a validation of his leave.

Of course his employer can simply dock him a days pay for an unexcused absence if you don't if they require some sort of justification.

Yes, she can do this. You haven't provided much detail here - I am going to assume that your husband isn't allowed to take off without clearing it with his boss first, but he did in this case (for obvious reasons). It sounds like his boss is simply asking for proof that it was indeed an emergency. He could refuse to provide the papers to his employer, but the consequences may not be good - being AWOL can be grounds for dismissal with many employers.

I agree with the others, show them some proof if illness. Grandpa always said to not get into a wee wee match with a skunk, it always comes out bad even if you win. You could also ask you doctor to write a brief note stating your busband accompanied you for treatment.