A woman attempted to kill herself but she repented before she died

I had a sister who was married and had three children. She was always having arguments with her husband, and she also had a disagreement with her father. The reason was that her husband treated her very harshly, which made her leave the house and go to the house of her mother, who was divorced and was married to someone else. Her mother’s husband also treated her badly. I – her brother – went and got her an apartment where she could live with me, but she often used to go to her mother. One time her mother’s husband forced her to go and leave her children with her husband, and she did that just to please her mother. One day there was an argument between her and her mother’s husband, and she went to her apartment, very upset about the calamities that had befallen her and the fact that her children had been taken away. She went and took some pills from the fridge and swallowed them all in an attempt to end her life. I took her to the hospital and had her treated. Before she died, she realized that she was about to die and she repented and started to pray a great deal for forgiveness for what she had done. She asked us to pray for forgiveness for her. Allaah willed that she should pass away. What is her situation now? Is it permissible for me to give charity and perform Hajj on her behalf? Please note that I vowed to do these actions all my life in sha Allah.

Praise be to Allaah.
So long as your sister repented to Allaah for what she did of trying to commit suicide, there is the hope that she may be forgiven. Repentance wipes out what came before it, and the one who repents from sin is like one who did not sin at all, as was narrated in saheeh ahaadeeth from the Prophet (peace and blessings of Allaah be upon him). If you give in charity on her behalf or pray for forgiveness for her or make du’aa’ for her, that is good; it will benefit her and you will be rewarded for it. You have to fulfil the vows you made to do those acts of worship, because Allaah has praised those who fulfil their vows in the verse in which He praises the righteous:

“They (are those who) fulfil (their) vows, and they fear a Day whose evil will be wide-spreading”

[al-Insaan 76:7 – interpretation of the meaning]

And the Prophet (peace and blessings of Allaah be upon him) said: “Whoever vows to obey Allaah, let him obey Him, and whoever vows to disobey Allaah, then he should not disobey Him.” (Narrated by Imam al-Bukhaari in his Saheeh)