Praise be to Allah.
If a Muslim dies, then all his wealth and dues such as pension, savings and lump sum payment on retirement go to his designated shar‘i heirs after his death. In your case, they are: the husband, the father, the mother and three daughters. So that wealth must be divided among these people in accordance with the shar‘i rulings on division of the estate, as follows:
The husband gets one quarter, as Allah may He be exalted, says (interpretation of the meaning):
“but if they have a child, then for you is one fourth of what they leave behind”
The father gets one sixth, as Allah may He be exalted, says (interpretation of the meaning):
“for his parents, for each one of the two is a sixth of what he has left, if he (- the deceased) has a child”
The mother also gets one sixth, based on the verse quoted above.
The two daughters get two thirds, because Allah, may He be glorified and exalted, says (interpretation of the meaning):
“but if they be all females (two or) more than two, for them is two thirds of what he (- the deceased) has left”
So the estate should be divided into forty-five parts: nine parts for the husband, six parts for the father, six parts for the mother, and eight parts for each daughter.
Your wife did well to affirm in her will that her wealth must be divided in full accordance with the shar‘i rulings on division of the estate, because she has adhered to the limits set by Allah even after her death. May Allah reward her with good, have mercy on her, and accept her with Him among His righteous slaves. Allah says – following the verses on inheritance quoted above – (interpretation of the meaning):
“These are the limits (of the law imposed) by Allah, and who obeys Allah and His Messenger He will admit them into Gardens served with running streams; therein they shall abide for ever; and that is a great achievement.
But whoso disobeys Allah and His Messenger and transgresses the limits imposed by Him He will make him enter Fire where he shall abide long, and for him is a humiliating punishment”
Moreover, the rulings mentioned above include all of your wife’s property, both movable and immovable, and also include her share of the car. With your wife’s death, her share is now commonly owned between all the heirs, each according to his designated share. If you need to use it, then it is essential to ask permission from the adult heirs, such as her father and mother. However we think that it is more appropriate in this case for you to buy the car from the rest of the heirs, and give each one his or her share of it, even if by instalments, so that you will be able to use it when you need to without any problem, if you need to do that, or you can sell it and add its price to the estate.
There is no exception to the ruling mentioned above concerning wealth except with regard to one matter only, which is the money that the company gives as a reward to whomever it sees fit of her relatives. This is not a right of your deceased wife. Some companies give a gift to the sons and daughters of the deceased; it is not permissible to divide this among all the heirs, rather it is the right only of the daughters, because it was given to them from the company’s own money, and it was not one of the rights of the deceased mother. This is an important matter to which one must pay attention.
It should be noted that the one who is patient with regard to his daughters, and takes care of them and raises them properly, especially when they have lost their mother, and strives hard to compensate them for what they have lost, seeking reward with his Lord for his efforts, will have a great reward with Allah, may He be exalted.
It was narrated that Anas ibn Maalik (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: : “Whoever takes care of two girls until they reach puberty, he and I will come like this on the Day of Resurrection” – and he held his two fingers together.
Narrated by Muslim (2631)
It was narrated that ‘Uqbah ibn ‘Aamir (may Allah be pleased with him) said: I heard the Prophet (blessings and peace of Allah be upon him) say: “Whoever has three daughters and is patient with them, and gives them food and drink, and clothes them from his wealth, they will be a screen for him from the Fire.”
Narrated by Imam Ahmad in al-Musnad (28/622 – Mu’sasat ar-Risaalah edition). The commentators said: Its isnaad is saheeh. It was also classed as saheeh by al-Albaani in Saheeh Ibn Maajah (no. 3669).
And Allah knows best.