> ok segir, at hann hefir fundit epli þau, er henni munu gripir í þykkja,
> and says he has found some apples (got lost here) that she

could/might pick

Zoega:

gripr (-ar, -ir), m. (1) costly thing; valuable treasure, property;
(2) value, money's worth; enn þriðja hlut á hann, þann er mikill g. er
í, that is of great value; epli þau, er henni munu gripir í þykkja,
apples which she will think of great value.

> ok bað, at hon skal hafa með sér sín epli ok bera saman ok hin.
> and asked her to have with her the apples (of her own) to compare if

they were the same (as the others)

Yes, "have her own apples with her and compare them (her apples) with
the others (the non-existent ones he's going to show her!)"