I recently had a miscarriage. My doctor wants me to continue prenatal pills. Is it ok to drink tea that has antioxidants?

Sure. Anything you like to drink is fine just after a miscarriage, so long as it makes you feel good.
OK. Most of teas on the market have antioxidants whether they advertise it or not. Taking prenatal vitamns will give the extra iron to replace the blood iron loss throught the miscarriage. The extra Folic Acid also may help with future pregnancy which may happer soon.