NZ 3 years parent visitor visa

Hi,

I am a NZ Resident and my mother is Indian citizen and she is currently in India. She is retired now.

My father expired this month and therefore I will like my mother to visit me on family visa ( Standard Visitor Visa) valid for 10 years.

Could you kindly tell me which documents I need to submit from my side to help the visa process for my mother? I prefer 3 years multiple entry parent grandparent visitor visa .
she has travelled to europe once but not in NZ . I have heard that in the first application 3 year visa is not granted . any clues?

Could you also tell me which documents my mother can take to the Embassy to submit her case?

Many thanks