There is nothing wrong with the name Nadiyya. There are many common Sahabiyyah names (such as Fatimah and Khadijah) that do not have a meaning related to Islam. Nadiyyah means “fresh”, “lush”, “bountiful”, though its literal meaning is “wet from rain” (something that is wet due to rain). However, it is possible you are referring to Naadiyah, which has the same meanings as Nadiyyah, but also has the meaning of “call”, “proclamation”.
Mardiyyah, which can also be written as Marziyyah, means “content”, and also means “someone who has earned Allah’s favor and pleasure”. This too is a good name.