Can you please mention the fact that my grandmother passed away in the middle of the semester and it had a major effect on my performance, basically, include the following in the letter:

I have been suspended from university and they requested a letter to explain why my performance was week. Can you please mention the fact that my grandmother passed away in the middle of the semester and it had a major effect on my performance, basically, include the following in the letter: express regrets then show my reasoning(adding to my grandmother death can you please add more convincing reasons) then future plans to help me be more successful in my university career.