Ian Stevenson's case collections, from Twenty Cases Suggestive of Reincarnation (1966) onward, typically involved intermissions of months to a few years between a death and a child's claimed memories of that life. Separately, apparition research from the SPR's Census of Hallucinations (1894) through G.N.M. Tyrrell's Apparitions (1953) cataloged encounters with figures long dead. Both literatures are real and peer-reviewed within their field.
Proposed reconciliations include the oversoul or higher-self model, where only a fragment incarnates while a core persists, and the psychic-imprint model, where what greets the dying is a recording rather than a person. Both have been argued seriously by survival researchers since the nineteenth century.
A harder reading holds that familiar figures at death may be constructs or simulacra assembled by an intermediary intelligence, which would make the welcoming light a reception desk rather than the destination.
If your grandmother was reborn thirty years ago, who or what is greeting experiencers at the tunnel's end wearing her face?