Arguably farmers would probably have been relatively safe from Viking raids. In fact the major targets for Vikings, based on our sources, were monasteries, trading sites, and "cities", which makes sense as these are the locations where you most stand to make a profit either from booty and slaves or from ransom. And of course, more to your question, monasteries were far less likely to have fighting men present which made them attractive.

On a larger note, we do have references to attempts by kings in France and England to set up coast guards in order to prevent Viking incursions. The Royal Frankish Annals, the major historical source for France in the 8th and early ninth century, states that Charlemagne ordered the construction of ships and a lighthouse in the first decade of the ninth century. His son, Louis the Pious also attempted to set up a similar system. And the first major Viking incursion discussed in the Anglo Saxon Chronicles is in fact a clash between Vikings and what appears to be a force guarding the coast.

Over all these measures seem to have had only moderate success, in large part because these forces had to watch the entire coast while Vikings only had to look for a place that was unguarded. Local resentment to royal power also played a part in the inability to successfully create effective early warning and deterrence systems.

All that being said, we do know that Vikings lived off the land in France and England and traveled over-land, at times in large numbers, so if you were a farmer and Vikings decided to take your horses/daughters/etc. while they were moving towards richer targets you were probably screwed. We don't really have records of this since peasants/farmers didn't write and those who did cared more about important sites and major battles not the plight of the every day man.

One option for these people would be to seek shelter in the walls of nearby cities, and we certainly see an increase in the building of walls and fortifications around urban sites in the second half of the ninth century as raiding increased and Vikings spent more time on land.

We also hear of multiple occasions where local lords (and sometimes even kings) would gather forces and respond to Viking incursions. These don't always result in violence as much of the time neither side wanted to risk open battle and would instead seek to negotiate a way out of the clash. When they did, the results seem to have been largely up in the air, both sides had an equal chance of winning (which of course is why they so often negotiated).

Hope that answers your question! The Royal Frankish Annals and the Anglo-Saxon Chronicle are both available in translation if you want to see the primary sources and actually Toronto University has a great source book called simply The Viking Age which has a bunch of great primary sources in translation as well.