On her marriage she gets listed as Elizabeth Eleanor Charlotte Augusta Bowes Cavendish Lyon, widow of George Crowe, and signs E C A Lyon Crowe. On the indexation of her marriage contract she got listed as Elizabeth E. C. A. C. Lyon only. Not found that notary's acts anywhere accessible so far.
Funeral lists Elizabeth A.C. B.C. Lyon.
on her Platt children's marriages the last name is only Lyon or Lyons.
I think the Bowes Cavendish may come from her mother, and her LNAB would be Lyon. Certainly doesn't use Bowes-Lyon anywhere. No trace of her earlier marriage or husband here that I can find on a quick search, so may be a migrant. Did you find her on 1825 census perchance?