Yes, she has to observe iddah for a period of 4 months and 10 days.
She cannot travel during the Iddah period or aftewards without a mahram.

1) My mom is 69 years old and long since post menopausal. Does she have to observe iddah (my father passed away 5 days ago) As in old age woman don’t have to wear hijab. 2) can she travel from Saudi Arabia to Australia alone, to be with my sister & her husband, they are expecting a baby in December.