Wa `alaykumus salaam wa rahmatullaah
Innaa lillaahi wa innaa ilayhi raaji`oon.
May Allaah enable you and your family to remain patient. Indeed Allaah, Himself, gives glad tidings to the patient ones: " And give glad tidings to the patient ones. Who, when afflicted with calamity, say: "Truly! To Allah we belong and truly, to Him we shall return. They are those on whom are the Salawat (i.e. blessings, etc.) (i.e. who are blessed and will be forgiven) from their Lord, and (they are those who) receive His Mercy, and it is they who are the guided-ones"
So inshaa'Allaah adorn yourself with this great character my beloved brother, for this is from the characteristics of the people of Jannah.
Also make a lot of du`aa for your father as this will benefit him in his grave inshaa'Allaah, as the Messenger of Allaah :saw2: said: “When a person dies, all his good deeds come to an end except three: ongoing charity, or beneficial knowledge, or a righteous child who will pray for him.” [Narrated by Muslim]
And inshaa'Allaah do give charity on his behalf as well, as this will reach your father. It was narrated by Sa’d ibn ‘Ubaadah that his mother died when he was absent, and he said: “O Messenger of Allaah, my mother has died when I was absent. Will it benefit her if I give in charity on her behalf?” He said: “Yes.” He said: “I ask you to bear witness that my garden that bears fruit is given in charity on her behalf.” Narrated by al-Bukhaari, 2756.
May Allaah accept your father to be from the people of Jannatil firdaws. Aameen
Wassalaamu `alaykum