Write an apology email to your HR manager requesting him to grant leave as your grandmother is suffering from heart problem.
Left -- not done -- train weekend – apologize – sister – requested -- will not happen again.

• Dear sir,
  With due regards i want to state that i want leave for three days because my grandmother is suffering from heart problem. so i left for my home yesterday. And the project will not be able to done at the decided time. I did reservation to come back for this weekend train. i apologize that i left without informing u. My sister requested me to reach at home as soon as possible that why i had to leave at night. and i ll make sure the this ll not happen again.
  
  Regards
  ABC
• 9 years agoHelpfull: Yes(18) No(1)
• Dear sir,
  I am very sorry to inform you that I have left the office by the weekend train for a certain day to see my grand mother who is suffering from heart problem.My sister has requested me a lot to see my grandmother.I know I have not done your work.I have not get any time to inform you.This kind of situation will not happen again.So, Sir in that case if you apologize me I will be pleased to you.
  Thanks & regards
  Koushik Das
• 9 years agoHelpfull: Yes(2) No(7)
• Dear sir,
  With due respect i state that my grandmother is suffering from heart problem so i need to go home for three days as soon as possible, so i left after office hours.The assignment what is to be submitted is not done yet.I booked return ticket of a weekend train but missed it and for that i apologize as i went uninformed.My sister requested to me come as soon as possible so i left immediately.I promise it will not happen again in future.
  
  Regards
  INDIA
• 9 years agoHelpfull: Yes(1) No(0)
• Respected Sir,
  I am very sory to inform you that due to my grandmothers deteoriating cardiac issuesI wont be able to complete the assignment immedately and portions of it will be left undone. I will have to leave this weekend and train reservation will be done henceforth.
  I extremely apologize to you for this nconvinience but my sister requested me to come and handle the matters there. I would be highly obliged to you if you grant me the leave and with that i also promise that this wil never happen again.
  With Regards,
  Thanking you,
  Yours faithfully,
  Trisha.
  
• 9 years agoHelpfull: Yes(1) No(0)
• Dear Sir,
  The purpose of this email is to apologize to grant emergency leave.I left my project not done.My grandmother is suffering from heart problem.And her condition is very critical.My sister requested me to come home as soon as possible.So i am going there by train weekend.
  And I will make sure that I will never happen again.
  Thanks and Regards
• 9 years agoHelpfull: Yes(0) No(0)