HE L P!

So as some of you ladies know DH and I bought a house and we are moving in this FRIDAY. I am very excited. Currently we live in an appartment at DH's parent's house. They were nice enough to rent us the apartment upstairs which is huge and were charging us really low rent. They wanted to help us save money for the house which we are so thankful for. I've been thinking of doing something special for them as a THANK YOU for holding us upstairs for 1.5 years and I don't know what to doooo or give them? ANY SUGGESTIONS??

T.I.A