The Great Reward for Those Who migrate in the Cause of Allah
Allah tells us that those who migrate for the sake of Allah, seeking to earn His pleasure and that which is with Him, leaving behind their homelands, families and friends, leaving their countries for the sake of Allah and His Messenger to support His religion, then they are killed, i.e., in Jihad, or they die, i.e., they pass away without being involved in fighting, they will have earned an immense reward. As Allah says:
(And whosoever leaves his home as an emigrant unto Allah and His Messenger, and death overtakes him, his reward is then surely incumbent upon Allah) 4:100
Those people who had left their hearth and homes in the cause of Allah and were killed or died of natural death, they would definitely be rewarded. If they have not benefited in this world, their reward will be there in the Hereafter.
Tazkirul Quran
Maulana Wahiduddin Khan
A man who is sincere in his faith, tolerates the sacrifice of anything belonging to him. The one thing he is not prepared to sacrifice is his faith. In pursuing this course, if he is required to leave his home, he leaves it, and if he has to give something, he gives it. He is tied to faith forever until he dies. Those who prove in the life of this world that they consider their faith to be the most valuable thing, will be highly appreciated by God and they will be given the most valuable thing in the life hereafter. There they will spend an eternal life of comfort and happiness.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.