Presuming that her grandmother organised the baptism when Adelaide was placed in her care, that might indicate that she arrived in England sometime late 1890/early 1891.
There is a (familysearch.org has the image) Alice Holder, a widow b. Apr 1865 England, married 18 years, mother of one child, one living, at the "Craig Colony for Epileptics, Livingston, New York". Is this possibly Adelaide's mother? I cannot find a marriage/birth, but I think that New York state records (as opposed to New York city) are a bit tricky, so maybe that's the problem.