"Abadoned" cars

My husband has had 2 cars he owns, stored in his mother's back, fenced- in yard, next to the garage, for several years. He has been unable to move them due to a disability five years ago. His mother received a certified letter from the village, stating that $750. (2 tickets) must be paid in less than one month.

This is the first and only letter received regarding the cars; no warnings, etc. Also, apparently the officer opened her gate and came into the back yard without her knowledge to search the property (she was not home).

What would be the best plan of action? Attend the court date; pay the fine? Also, why was there no warning....just a massive fine? Can a police office come onto your property and search with no order or warning?
Thanks for any advice.

Not sure about your state or county laws, but here in California you can be ordered to remove such vehicles if complaints arise from neighbors. (not many like Sanford and Son's living next door) I have a hobby of restoring old cars and see this happen all the time.
First off, I highly doubt you should be fined without warning. Any instance I have heard of, the city will give fair notice before issuing any form of ticket or order to remove such vehicles. Also, it has to be a court order to do so. The vehicles can remain if you show just cause you have intentions of either restoring or repairing such vehicles.
How do you know the police entered the premise? Vehicle ID #'s are or would be the dead give away they entered without permission. If the notice just shows vehicles make and model, then it's hard to say they entered the property.

Go to your city hall/courthouse or police department and get the inside scoop of what the proper procedure should be.

Everything the police officer and city did was technically legal. If a police officer /department recieved a complaint, they do not need permission or a warrant to enter the premises, especially if the vehicle were in plain sight (and most states laws state that unless the vehicles are parked in a completely enclosed and secure garage, they are in plain sight - even in fenced-in areas). Also, about the Vechile Identification Numbers being proof that the officer entered the premises, this is not true. The National Crime Information Center (NCIC) and most state law enforcement information networks (LEIN) keep records of vehicles owned by individuals. With just a few minutes of computer work, a police officer or dispatcher could easily cross reference an address to find a name, and then find out what cars such person owns (or has owned). I would suggest that you pay the fines, and remove the vehicles to avoid further fines.