I haven't seen anyone point this out yet, so I will. Adrien's desire to turn his house into a museum ties perfectly into his arc all season. He starts the season out not wanting to go home. Not wanting to go home so badly that he turns around and starts running away.
And all season we see him unable to get comfortable in that house. His stuff is in boxes. He can't figure out how to paint his walls. He doesn't feel at home there. The whole place already feels like a museum or mausoleum to his father's life. And suddenly he gets an idea. "What if it really WAS a museum?"
What if instead of having to live in the shadow of his father, he could make the house into what it already is. A monument to a man he never knew and never understood. An archive of the past. Something OTHER than a home. Because it doesn't feel like a home to him, it hasn't in a long long time. Yes Marinette contributed to his idea of "making people see the great man Gabriel was." But it's really not about that, it's about making the house make sense to him, and having an excuse to get out. Because you can't LIVE in a museum. Can you. The museum idea is Adrien finding a way to get out from under the house....the only way he has found that feels socially acceptable.