
Most folks have a difficult time coming to the point of suing a relative, but I think (if you have not left out any important details) you probably have a case against her. See a good real estate lawyer in your area who spends a good portion of his time in court. Be sure to explain in complete detail what agreements were made (even if oral) concerning the placement of the mobile home; what difficulties it might have been to your mother; what time frames were agreed to - if any - for the mobile home to be left there, etc.
Note: Many real estate lawyers are not "trial" lawyers. The lawyer you consult should be one who is comfortable in court but who knows real estate law.