Neither is correct; no apostrophe is needed with this construction. However, if you said '...at our neighbours' house', the apostrophe goes at the end if more than one person lives there, or before the 's' if the neighbour lives alone.
My neighbour's house (one person)
My neighbours' house (more than one)
The house of my neighbour
The house of my ...
The answer is 1. But please note that there is a basic syntax problem. You don't say both "of" and "’s", so the correct syntax is:
We had Thanksgiving dinner at our neighbor’s house.
Or: We had Thanksgiving dinner at our neighbors’ house.
Or with “of”: We had Thanksgiving dinner at the house of our neighbors.
But it also depends on what you ...
Actually, I would have said that in the first sentence, "Netflix" operates as a noun modifying the word "subscriber," just as it does in the phrase "Netflix subscription." Note phrases like "magazine subscribers," "television viewers," and "radio listeners" which would never have the first word in possessive form.