If you are returning to your native land and your passport is from there you will be allowed back into your country. If you are leaving your native land and your passport will expire in 6 months or less you can be refused entry into a different country. It is the discretion of the Customs Officer weather they allow you into their country. They may also not grant your grandaughter 180 days because of the short validity date of the passport as it would not be current during her stay.