I can't find a specific answer to your question on the MD tax website, but in my opinion if you are still on active duty, and assuming your SLR is still NH, by federal law (the VBTA Act of 2018), your non-military spouse may clam NH as her state of residence or domicile for tax purposes. Therefore she may legitimately answer Yes to question 1c on MD Form MW507M.
Section 302 (b) of the VBTA states that the spouse may elect to use the servicemember's state of residence for tax purposes "with respect to any return of state or local income tax for any taxable year" following the passage of the act.
https://www.congress.gov/bill/115th-congress/senate-bill/2248/text
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
