Is a husband considered a martyr if he dies while seeking knowledge and providing for his family, and is she sinful for building a structure over his grave despite his objection to it, and is it permissible to move his body to another grave that conforms to Sharia?

Firstly: Whoever goes out to earn a living for his family or his parents, or to keep himself chaste, is considered to be in the path of Allah. And whoever goes out to seek knowledge is upon great good.

Secondly: It is permissible to transfer the deceased to another country for a valid purpose, such as to comfort their family and enable them to visit the grave, provided there is no fear of the body decomposing or its sanctity being violated.

Thirdly: The Sunnah is that the grave should not be raised more than a span. Building upon it is forbidden, and the use of cement or fired bricks is disliked unless there is a need, such as fearing excavation by wild animals or damage from floods.

Fourthly: It is permissible to exhume a grave and move the deceased after burial for a valid purpose, such as if they were buried without ritual washing (ghusl), or in a usurped place, or to move them from the path of a flood, or to separate them from someone buried with them.