It's either of those.
I'm not sure whether it's a matter of regional or personal preference but you'll find people pronouncing ντ μπ γκ as "nd mb ng" or as "d b g".
I don't think there are any pairs of words that are pronounced the same except that one has "nd" and the other has "d", so it's not that important which version you use.
As a learner, perhaps you could use the rule of thumb that you use "b d g" at the beginning of a syllable and "mb nd ng" between vowels, i.e. "nd" here.