I moved into the country in a mobile home and started renting then a year later we decided to purchase the land and mobile home on contract. We have paid taxes and insurance on it. 2 years later we find the person selling it to us does not have the title to mobile home just to land. Does he have the right to hold us to this contract? Who would be the rightful owner to the mobile home?

Where you are at, the age of the mobile home all go into it. In many places a mobile home is just like a car, it has a title and you pay personal property tax on it, just like a car. So who ever holds that title owns it,

The seller needs to clear up the title issue prior to you buying it.

Next most contracts for deed can not force you to keep the contract, most allow you to back out anytime, merely you loose what you have paid into it, since it converts to a rental situation.

The rightful owner of the mobile home is the person who has the title to it, no one else.