You spent the holidays at a friend's house, you need to write a letter to thank his/her parents for allowing him to spend it there. Write letter in three paragraphs:
1. short paragraph on asking about their health
2. start the letter on thanking them.
3. Summarize the letter and say bye

Dear (last name of friend) family,

It is within my deepest regards that I thank you for granting me a place to stay over the holidays. It is impossible to describe the gratitude I feel for your kindness. (friend’s name) and I shared many incredible moments during my stay at your beautiful home; moments I will forever cherish in the form of fond memories.

How have you guys been faring since I left? Has (friend’s name) gotten into anymore accidents since I left? If they have, please remind them to take it easy and to stay away from any glass doors for a while.

In short, I hope you all are getting on well! I appreciate your generosity beyond that which is comprehensible to the human mind. I look forward to seeing you all again soon!

Best regards,
(your name)