Tax Year 2016: In 2016 we moved for a job, and a friend and Nephew help move us. Can their flights back home be deduction as a moving expense?

Yes, that can be included as part of moving costs.  They were there for the sole purpose to help you move.

You can deduct the cost of transportation and lodging for yourself and members of your household while traveling from your former home to your new home. This includes expenses for the day you arrive.  However, you may not include any expenses for food.

The day of arrival is the day you secure lodging at the new place of residence, even if the lodging is on a temporary basis.  You can include any lodging expenses you had in the area of your former home within one day after you could no longer live in your former home because your furniture had been moved.

You can deduct the cost to transport your belongings. You can include the cost of storing and insuring household goods and personal effects within any period of 30 consecutive days after the day your things are moved from your former home and before they are delivered to your new home.

This IRS Publication may be helpful too IRS Pub 521 Moving Expenses