My son and his girlfriend just had a baby. Her parents told her she had to move out when the stepdad found out she was pregnant. They want to get married but will she need consent in Ohio.?

Yes, if she is under the age of 18. If the parents refuse to give consent, they could apply to the courts for a court order. The court might grant the consent if there is adequate evidence that they can raise the child and have the ability to support and take care of it.