Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [name],
I just want to say thank you dearly for allowing me to stay with you and your family during my visit. You were more than hospitable and I cannot describe the warmth I felt while visiting with you.
If you are ever in my area, please know that my home is also yours. Thank you for a relaxing and wonderful time.
Best regards,