Daughter- early 20s- arriving in Athens on a late flight- would be getting there around 1 am. Will be going to a hostel- location to be determined.

Will there be transportation for her to take at that hour? Thanks-

She should take a taxi, they are very safe, but it might be good for her to discuss the price beforehand, or she might have a surprise.

Or the bus. See www.athensinfoguide.com/gettingaroundbus.htm - but the metro stops earlier.

taxi- how much would that be? And are they available that late (or should I say early!)

Would the bus be safe? She wouldn't be the only one on it?

Taxi's that late (after midnight) are very expensive... usually from city center to airport they are around 32 euro but after midnight the cost can go up to around 60 euro.
But, they are plentiful.

The express bus runs all night and is very safe. But getting from the downtown bus stop at Syntagma Sq. to her hostel might then prove difficult.

thanks for all the helpful information. Maybe she should stay at the airport overnight and then travel into the city in the morning- are there hotels at the airport?

IF you want to pay 250-300E for her to stay at the airport, ok!

But why not take the (VERY SAFE) bus which goes every 30 minutes allnight long. When she gets out of bus on SYntagma Square, with her Map in hand and her hostel marked clearly, she can get a taxi THEN to the hostel.. will cost her 5-6 Euros instead of 60+. And yes, taxis are plentiful in Syntagma even at 3 in the wee hours; Athens stays up late.

Didn't you say she's early 20s? If she were mid-teens I could understand some anxiety, but she's an adult and she'll be in Greece, for heaven's sake - no need to worry.