Welcome to the Forum Milt:
The water lines (including the water heater) will need to be drained down and blown out with air to be sure there are no low spots holding water. The commode tanks should be drained and antifreeze poured into the commode bowl, and all other traps (you can get the antifreeze from an RV dealer).
Leave the heat off; modulars sit on lots everywhere without heat in them. Mould should not be a problem and a few bunches of eucalyptus will give you a pleasant "Welcome home", next summer.