I understand your question as "is Meroitic a Nubian language", or perhaps better "was Meroitic a Nubian language" - since it's extinct.
Well, we don't know and we might never really know. The problems is that we don't have a lot of Material and no speakers.
The best known classification proposal (by Claude Rilly) does in fact place it among other Nubian languages: but it's just a proposal, our best guess. We might never actually know for sure.
