There is a legal requirement to arrange burial or cremation in a timely manner.

Burial & Cremation Act 1964 section 46E: Bodies to be disposed of within reasonable time

(1) A person having charge of a body must, within a reasonable time of taking charge of it,—
(a) dispose of it; or
(b) cause it to be disposed of; or
(c) transfer charge of it to another person for—
  1. disposal; or
  2. removal for anatomical examination under the Human Tissue Act 2008; or
  3. removal from New Zealand for disposal outside New Zealand.

(2) This section is subject to any enactment to the contrary.