MD 2017 refund Tax rec'd in 2018. Must MD Refund be Reported as 2018 Income on Both 2018 Fed Tax and on 2018 MD Tax ?

Just federal.  A State Tax Refund is taxable if you itemized deductions on that prior year's federal return and took a deduction for state income taxes instead of the sale tax.  You got a deduction benefit for it so now you have to include it as income. If you took the standard deduction or filed a 1040EZ or 1040A it is not taxable and you don't need to report it.

To enter a state refund just type  1099-G (with the dash)  in the search box at the top of your return and click on Jump To it.
 
OR  Enter the 1099G under
 Federal on left
Wages & Income at top
 Scroll down to 1099-Misc and  Other Common Income
      You might need click on Show More to expand the section

Then it's the first line for Refunds Received for State/Local Tax Returns - Click Start
     You do not want the next line that says Other 1099G Income
 
On the first screen check YES - Received a State Refund.