Stock Certificates and chain of inheritance

This might be a little complicated, but bear with me. My mom's BF passed a couple of weeks ago. In his safe were stock certificates under his mother's name. We know that he is the beneficiary of her estate, and my mom is the beneficiary of her BF's estate. I reached out to computershare as the certificates are mostly for communication companies that have been absorbed by at&t over the last 40 years and was told that at&t uses computershare as their transfer agent. The guy over the phone at computershare told me they need the social of the original owner of the certificate, and then we can move on from there. Are these even worth it? It is only 120 shares and ideally I would like them transferred into my mom's name or under the estate account of her BF, but this is all new territory for me. Any help would be appreciated.