If your family has physical access to your device when you're gone, all they need to know is your password. If they don't, they will also need your seed phrase. It's up to you to choose how you want to pass on this information. Your family is always welcome to drop us a line so we can point them towards the right direction so please make sure you include our contact details along with your instructions.
We recommend you provide them our email support@coinomi.com or give them our official website support.coinomi.com to find support related materials