How do I tell my host family? 10 points for the best advice. Thank you?

[hope]

I was an exchange student 5 years ago. I continue to pursue my education in the United States. I recently graduates without job. I am planning to go back to Thailand (My home). Last year, I promised my host that I will take her and her son to Thailand with me. They really want to travel there. This year things are little differences--I have been working part-time in the past 6 months. I have been unemployed for a month now. I only have $5000 in my bank account. It will be gone if I buy 3 plane tickets to Thailand. I wish I could save those money because the world economy are rough and just in case I don't find a good job right away. My parents claim they will support me when I am in Thailand. We need to take my host family here if they want to come becasue they have been taking good care of me for many years. I know my parents are generous, but I just don't want to ask them for money for rents and food again. I want to secure my last $5000. Please help.

Will my host family understand me? Will they angry? How do I tell them?

Thank you
I never offer to buy a plane ticket. They can go and stay there for free, but my parents want me to buy the plane ticket too.