Hello lollyrock,
You may already have this info about the husband Michael Jackson?
If this is the correct person he died 6 Dec 1891 aged 55 years (implied DoB - 1836)
Here is a newspaper article about his death.

The many friends of Mr Michael Jackson, of the Christchurch road, will be sorry to learn that he has succumbed to that scourge of modern times — influenza. He has been ailing for the past few weeks but was not considered to be seriously ill until within the last few days. The funeral leaves Zeigler's hotel, Kumara, for the Hokitika cemetery tomorrow morning at ten o'clock arriving at the cemetery at half-past one.
West Coast Times, Issue 9194, 8 December 1891.

Here is the link to the Hokitika Cemetery - his interment details and a picture of his headstone and his wife's name and DoD can be seen here.
His wife is named as Jane 'a native of Inverness, Scotland' Jane died 6 Sept 1903.
http://e-search.westlanddc.govt.nz/cemeteries/result.php?v=21470

DEATH.
Jackson— On September 6th, at her residence, Jackson's, Christchurch Road, Jane Jackson, native of Inverness, Scotland. Aged 64 years. Deeply regretted.
West Coast Times, Issue 12607, 8 September 1903

FUNERAL NOTICE.
THE friends of MESSRS JACKSON BROTHERS are respectfully invited to follow the remains of their late mother (Jane), to the place of interment, Hokitika Cemetery. The funeral cortege will move from Preston’s Criterion Hotel, Seddon Street, on WEDNESDAY, 9th inst., at 9 30 a.m., arriving at Hokitika at 2 p.m:
H. JOHNSON, Undertaker.
Greymouth Evening Star, 8 September 1903

General regret over a wide area will be felt at the death of Mrs Jackson, senr, of the well known hostelry on the Christchurch road. The old lady closed a long and highly respected career by her decease on Sunday morning last. For over thirty years her home was one of the principal landmarks of the old travelling days and a centre of kindness and hospitality. She leaves a grown up family to mourn the loss of a good mother, and many residents of the Coast will long remember the old kindly face and pleasant homely welcome ever extended by the old lady. The funeral will be held today, leaving the Criterion Hotel, Kumara, at 9 30 am, and arriving at Hokitika at 2 p m, en route to the cemetery.
The Grey River Argus, 9 September 1903.

Thank you. I was enquiring for a friend who is descended from this couple. She would like to know her g.grandmother's maiden name and forebears genealogy.

If your friend buys Jane's death certificate, she might get lucky and find her maiden name listed?
Also, from what I've seen on Papers Past there were two sons - Thomas Jackson and David Alexander Jackson.

There is a marriage on BDM - 26 Feb 1895 between a Thomas Matheson Jackson and Mary Eden O'Shaughnessey. 1895/2743.

Matheson could be Jane's maiden surname?

David Alexander Jackson and his wife Wilhelmina (Mina) Hepburn are both buried in the Hokitika Cemetery.