You each joined a different server. All of his items and rights to his home are still in place on the 1.7 server.
Sorry for the confusion. Thank you for posting here.
You and your Grandson joined two different worlds/servers.
To join the 1.7 server you are familiar with, simply set your client to client version 1.7.10, and connect as usual to survival.famcraft.com. Make sure you and your Grandson both join with a 1.7 client to ensure you join the same world.
If you wish to visit the new 1.8 server which features combined chat with the 1.7 server (As in all players share a single chat to keep the community together) then start your client and select Minecraft client version 1.8, and connect to the usual address at survival.famcraft.com
We will always have our main survival server- it is not going anywhere. You can learn more about the addition of the new 1.8 server here:
https://famcraft.com/index.php/topic,9486.msg55225.html#msg55225 If we can be of any further assistance, please let us know.