Hello,
Probated will:
https://www.archway.archives.govt.nz/ViewFullItem.do?code=23017363&digital=yesCemetery details:
HOLDER, Stephen William
Last Address:   133 Clawton Street, New Plymouth
Age at Death:   59 Years
Date of Death:   10 Mar 1978
Category:   Ashes Burial
Funeral Director:   Vospers Funeral Home, 257 Devon Street East, NEW PLYMOUTH 4310, 
www.vospers.co.nzDate of Burial:   10 Mar 1978
Cemetery:   TE HENUI
Location in Cemetery:   Services Cremation Block B Plot 63
His wife?
HOLDER, FrancesLast Address:   Rhapsody Lifecare, 30 Mill Road New Plymouth
Age at Death:   86 Years
Date of Death:   28 Sep 2011
Category:   Cremation
Funeral Director:   Park View Funeral Home, (Was Carrington Funeral Home), 233 Carrington Street, NEW PLYMOUTH 4310
Date of Cremation:   4 Oct 2011
Type of Service:   Full
Ashes Disposal:   Funeral Director 10 Oct 2011
Her death notices appeared here:
Publications
 Taranaki Daily News (2)
You could contact the Taranaki library for a copy of the death notice, or approach the funeral directors:
https://vymaps.com/NZ/Carrington-Funeral-Home-501965/https://servicefinder.co.nz/profile/Park-View-Funeral-Home-122684Minniehaha.