Simply replace the unfilled areas such as "" and "[date]" with your information.
On behalf of my entire family, I want to thank you for your kind condolences as we grieved for the loss of our [family member], [Name].
If there had not been generous people there supporting and caring for us, we would not have been able to make it through all of the daunting tasks. I am truly touched by your generosity and thoughtfulness. I am especially thankful for [specific help or kindness] that you provided. I cannot begin to tell you how much I appreciated this help.
As I am sure you understand, the next few months will be difficult for my family as we try to move forward. It will help us to know that we have such [adjective] friends that we can turn to for support.