She explained she both wants a large house in the city, so that she can make visits the museums regularly, and also a cottage in the mountains, to which she can go on free weekends.

A) both wants a large house in the city, so that she can make visits the museums regularly, and also a cottage in the mountains, to which
B) wants both a large house in the city, for the purpose of visiting the museums regularly, and a cottage in the mountains, where
C) wants both a large house in the city, from which she can visit the museums regularly, and a cottage in the mountains, to which
D) wants both a large house in the city, so that she can make visits the museums regularly, and as well a cottage in the mountains, where
E) both wants a large house in the city, from which she can visit the museums regularly, and a cottage in the mountains, to which

both (A, E) vs wants (B, C, D)

A, E out because it gives an impression that there are two "shes" whereas in B,C,D talk about two homes.

D out because of "She can make visits the museums regularly"

B comparison of purposes inappropriate.

C correctly states that she wants two houses one in city and one in mountains. Assuming she lives in city, it also properly uses 'from' and 'to which' appropriately.