Genealogy / Male form of female surname [20]

My gr grandmother is listed as Katarzyna MRUCZKA, Is her husband's surname definitively MRUK or MRUCZEK or could it be either?

Genealogy / Male form of female surname [20]

Thanks for your time.

Genealogy / Male form of female surname [20]

So basically there is no grammatical rule to help trace back from the inflected form of the surname (MRUCZKA) to the inifinitive or male form of the surname (MRUK/MRUCZEK/MRUCZKA)?

Genealogy / Male form of female surname [20]

So to be clear, as I fill in the names on my WikiTree profile pages, I will use Katarzyna Mruczka and her father Wojciech Mruczka. I grew up in the 1970's when everyone here called us dumb Pollacks. Seriously, any nation of people that can manage grammar as complex as this is certainly not dumb. Thank you all for your help.