I have no idea if she remarried but she may have been living in Point Chevalier. 
*   Where does this address come from ?
*   How do you know that she may have been living at Pt. Chevalier ?
*   Why do you say "she must have died after 1970" ?
*   How do you know she emigrated to New Zealand (and to Auckland in particular) ?
*   What do you know about her son George ?  (Do you have a year of birth for him ?) 

~   Lu