My dad came here on Supervisa last year in July, Officer stamped it for 2 years until 2019 July, then we went to Mexico for vacation and came back into Canada, at that time Officer did not put any date on the stamp to return.

I know SuperVisa holder is eligible for 2 years to stay but after talking to few other people I am now confused, so please help around which is correct?

1) He does not need visa extension because officer did not put return date so automatically he is eligible to stay for 2 years from the date of his last entry?

2) He has only 6 months to stay and if he wishes to stay longer, he has to apply for extension.

3) He can stay until 2019 July based on the date when he entered first in July 2017 when officer did put in the return date.

Not sure which is correct??? 

Thanks,

Scorp