Yes, this is a remainder interest.

The interest held by the person is called a remainder interest. The person does NOT gain the benefit of their interest UNTIL the original owner's interest ends. 

OK, now for you reporting this I am assuming this has not been your personal residence for at least 2 of the previous 5 years.

You would show the sales price as your 50% share

Date of sale would be when sold in 2017.

Date of purchase would actually be date 12 years ago.

Cost of the home is the difficult one.  When you get a gift of 50% of the home, your cost basis is what your mother paid for the home (plus improvements) or the Fair Market Value when given 12 years ago, whichever is less.

So most likely it will be what she paid for it years ago, plus major improvements, plus then improvements you made over the last 12 years.  This would be your cost basis. 

Also be sure to take any closing costs on the sale, such as sales commissions, 

To enter your Investments sold

Click on Federal Taxes

Click on Wages and Income

Click on I'll choose what I work on

Scroll down to Investments

On Stocks, Bonds, Other, click the start or update button