Some people present such strong evidence of a bona fide marriage that the immigration services do not feel a need for interviews. No one here can opine whether your friend would be required to attend an interview as there are not enough facts in your post.
What your friend should look out for is being accused of having abandoned her legal permanent residency. On an LPR is outside the US, especially for long absences, the government may allege that the LPR is not maintaining residency in the US and may revoke the LPR's residency.
For these reasons, your friend should review her specific facts with her attorney.