Rs 50,000 should be entered in Line for "Income from Other Sources". This will also be the Gross Total Income if there is no other source of income from India and if the person is non-resident then income from non-Indian sources will not be applicable.
TDS should be entered in lines for "Details of Tax Deducted at Source on Income Other Than Salary". All details like TAN of the deductor, name of the deductor and amount of tax deducted must be filled in. If possible confirm this matches the tax credit shown for the person inf Form 26AS (which can be downloaded from the Income Tax website) and should also match the Form 16A that the deductor should have given to the person.
NRI can avail of the Rs 1,80,000 deduction. So, in this example there will be no tax since the Rs 50,000 income is less than Rs 1,80,000 slab and all TDS should be refunded.
Best way to file is to use online e-filing using Excel spreadsheet for ITR-1. This is also available on the Income Tax Dept website: https://incometaxindiaefiling.gov.in/portal/index.do