I agree with Susan.

If you take a look at Md. Tax-General Code Ann. §10-209, which governs the new subtraction, there is no reference to the death of a taxpayer or the surviving spouse.  The only reference to the entitlement in relation to a spouse is in subsection (b) where the spouse is totally disabled:

https://advance.lexis.com/documentpage/?pdmfid=1000516&crid=0664959b-7208-4fd5-92d2-26103412cf66&nod...

In contrast, if you refer to §10-754, which is for the Senior tax credit that was added by the same House Bill 1468, there are clear references to surviving spouses in two subsections:

https://advance.lexis.com/documentpage/?pdmfid=1000516&crid=10ab04ba-b5c8-4dae-ad8e-86b1a07bf0b1&nod...

If there was an intention for a surviving spouse to benefit from the subtraction, there would have been no reason for §10-209 to not include such references.