This particular verse (3:195) was revealed concerning the Muslims who were persecuted and eventually fled their homeland. The verse was revealed as a result of Umm Salamah’s talk with the Messenger of God, asking the Prophet (p) is there a reward for those women who migrated, expelled and fought against the oppressors?
Upon Umm Salamah’s saying, revelation came down comforting her that never will a reward of one who migrated, expelled or fought be wasted, be they men or women. Both will be rewarded for their work, nothing will go to waste (Tafsir al-Jalalayn, Tanwir al-Miqbas min Tafsîr Ibn ‘Abbas, Asbab Al-Nuzul by Al-Wahidi and Tafsir Ibn Kathir). 
“And their Lord responded to them, “Never will I allow to be lost the work of [any] worker among you, whether male or female; you are of one another. So those who emigrated or were evicted from their homes or were harmed in My cause or fought or were killed – I will surely remove from them their misdeeds, and I will surely admit them to gardens beneath which rivers flow as reward from Allah , and Allah has with Him the best reward.” – Quran 3:195
The above verse promises those Companions who migrated, fled from persecution or fought against the Quraysh, that they will be rewarded for their deeds. Their deeds won’t go to waste for all the good they did, be that male or female. The verse tells us that they will be rewarded with Paradise for their work (Tafsir al-Jalalayn, Tanwîr al-Miqbas min Tafsir Ibn ‘Abbas, Asbab Al-Nuzul by Al-Wahidi and Tafsir Ibn Kathir).
Tafsir Ibn kathir:
“…(“Never will I allow to be lost the work of any of you, be he male or female,) explains the type of answer Allah gave them, stating that no deed of any person is ever lost with Him. Rather, He will completely reward each person for his or her good deeds. Allah’s statement, (You are (members) one of another) means, you are all equal in relation to gaining My reward.
Therefore, (those who emigrated), by leaving the land of Shirk and migrating to the land of faith, leaving behind their loved ones, brethren, friends and neighbors, (and were driven out from their homes), when the Mushriks tormented them and forced them to migrate, (and suffered harm in My cause), for their only wrong, to the people, was that they believed in Allah Alone.
In similar Ayat, Allah said, (and have driven out the Messenger and yourselves because you believe in Allah your Lord!) ﴿ 60:1 ﴾, and, (And they had no fault except that they believed in Allah, the Almighty, Worthy of all praise!)…” 
Maulana Muhammad Ali:
“195a. This is a promise which includes all those companions of the Holy Prophet who fled from their homes, and those who were persecuted, and those who fought in his company. The concluding words of the verse show that the promise to make them enter Gardens relates to this life as well, and its fulfilment was brought about in the worldly achievements of the Muslims. The reward of the Hereafter is separately spoken of in the words, with Allah is the best reward.” 
Tafhim al-Qur’an – Sayyid Abul Ala Maududi:
“139 That is, “In My sight all of you are alike as human bungs and I have the same standards of justice and judgment for all, and men should not forget that women are of the same “human status as they themselves have. I do not discriminate between man and woman, master and slave, the black and the white, the high and the low.”
140 There is a Tradition that VV. 190-195 were recited by the Holy Prophet before some non-Muslims who came to him and said, “All the Prophets brought one Sign or the other with them. For instance, Moses had the miraculous staff and his bright hand to show, and Jesus healed the blind and the lepers. Please tell us what sign have you brought us as a proof of your Prophethood.” The Holy. Prophet recited these verses and said, “I have brought this.” 
Malik Ghulam Farid:
“549. As this surah mainly deals with Christian doctrines and ideals and with their way of life, and as Christianity, in spite of the claims of the Christian Church to the contrary, gives woman a status definitely inferior to that of man, the insistence on the equality of the status of woman with that of man in the spiritual sphere forms a befitting sequel to it. The words, you are from one another, are intended to emphasize this equality of status of both men and women.” 
 Narrated ‘Amr bin Dinar: from a man among the children of Umm Salamah, from Umm Salamah that she said: “O Messenger of Allah! I have not heard Allah mentioning anything about women and emigration.” So Allah, Blessed and Most High, revealed: “Never will I allow to be lost the work of any of you, be he male or female. You are members one of another (3:195).” (Jami at-Tirmidhi volume 5, Book 44, Hadith 3023) Grade : Hasan (Darussalam)
 Tafsir Ibn Kathir http://www.alim.org/library/quran/AlQuran-tafsir/TIK/3/195
 The Holy Quran Arabic Text with English Translation, Commentary and comprehensive Introduction [Year 2002 Edition] by Maulana Muhammad Ali, page 188
 Sayyid Abul Ala Maududi – Tafhim al-Qur’an – The Meaning of the Qur’an http://www.englishtafsir.com/Quran/3/index.html#sdfootnote142sym
 The Holy Qur’an – Arabic Text With English Translation & Short Commentary By Malik Ghulam Farid, page 176 – 177