。
She's always making fun of her husband.
Literal
She [topic-は] always her husband [object-を] is-fooling.
馬鹿にする (ばかにする, 'to make a fool of, to look down on, to ridicule') is a set expression treating someone as stupid. The 常に + ~ている combination emphasizes this is a persistent behavior pattern. 彼女の夫 (her husband) uses the possessive explicitly, which is natural in written Japanese.