Yes, if you have the 2016 desktop software and you have a family member who still needs to file a 2016 return it is fine to use the program to prepare their return. It cannot be e-filed, since e-filing is closed for 2016 returns. It has to be printed, signed and mailed.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS and/or your state received the return.