Stephanie,
When the owner (your grandfather) died, it was up to the new owner (your mother) to contact the operator to let them know, and provide them with the will or whatever other documentation showed the transfer so that they could begin paying the new owner. That being said, it sounds like you have been paying the assessment on the minerals in place, and it was the production assessment that was sold for the non-payment of taxes. If your grandfather's will was of record, your mother should have been identified during the title search as a person entitled to notice to redeem. However, assuming you have continued to pay the assessment on the minerals, it is my opinion that the production assessment was void because it was duplicative and you have superior title. Unfortunately, this is a common occurrence in West Virginia, because, although the State Auditor has declared that production assessments should not be sold at tax sales, some of them were. Most of the time, it is the result of an honest mistake that occurs due to the complexity of oil and gas title and assessment. You will need to bring a quiet title action against the purchaser at the tax sale, or their heirs, successors, or assigns. The three year statute of limitations does not apply because the assessment was void, therefore the tax deed was void.