Travelling without a Mahram

Q: Does a woman over 50 years require a Mahram when travelling within 77 km?

Q: Is it permissible for a female to take a flight on her own, if a mahram drops her on one side of the journey and a mahram picks her up on the other side? Basically for the duration of the flight there is no mahram.

Q: I am an unmarried working woman and my questions are:

1. Can I travel with a non mehram senior colleague through plane from Lahore to Karachi?

2. Can I stay in Karachi for a week with that senior colleague in separate rooms?

3. Can I go to visit Karachi beach with 3 male colleagues after office?

Please guide me in both the cases if I have option to avoid this situation and if I dont have an option to avoid. I shall be thankful to you for your timely guidance.

Q: What is the Shar'ee ruling in regard to women travelling for long distances alone?

Q: Is it permissible for a lady to travel with her father in law alone, or with a small baby, for a short distance (not musaafir)? What about for longer distances over 78km?