As mentioned above, things like energy bars work well. Prefer the ones in aluminum coated plastic packets as they are more airtight, and don't go rancid.
If you go with nuts, get ones that are sealed. Again, anthing that permits oxygen access to the nuts will cause the oils to go rancid. Nuts have the advantage of being about 1/3 fat. They have the disadvantage that, unless chewed thoroughly, large amounts pass through you undigested.
Another consideration, however is water. An easy and cheap way to store and carry this is to use 2 liter (2 quart) soda bottles: They seal well, and are tough. The thinner water bottle plastic can break if struck hard when full against a corner.
Water is more important that food. You can go weeks without food, days without water. Depending on your climate you may want 2 to 8 liters of water per day. (From experience in winter travel, and cool weather, 2 liters of water a day is the minimum. Backpacking I carry a 2 liter bottle to refill my 12 oz squeeze bottle. The dog caries and addition 4 500 ml bottles in his pack, and I have still run out of water above timberline toward the end of the day.
If you are in country that has water sources that you are willing to drink, you can replenish your water supply. My go to hiking area has abundant water below tree line.
But I would suggest 4 liters of water per day of walking time. If it's there, you can abandon it, either at the car or beside the road. If it's not there, well, your imagination is as good as mine. (A comment said 'No one is going to walk out with 5 gallons of water. If I had to walk out of Death Valley, I would, or even in many places in the Southwest.)
This illustrates a critical point however: You need to define the context of what sort of the situation:
Are you alone, or is there a chance you will have company?
Are your mobile, or fixed? Your question says mobile. What is your plan if you are with someone who is unable to walk out? Or YOU are unable to walk out?
Expected weather. Preparing for a trek in the Sonoran Desert in August is different from Wood Buffalo Park in January. The latter leaves you critically dependent on being able to melt snow for water.
Do you have the knowledge/skills/gear to be at least partially self sufficient? This slows you down a lot, but if you are unable to walk to a reasonable location in your two day window, staying put may make more sense. (The usual advice is "Stay with your vehicle": it's easier to find from the air.
For longer event storage, a 5 gallon pail of brown rice and lentils works well. The mixture makes a complete protein, and 1.5 to 2 lbs per day will allow reasonably hard work. It does take about 40 minutes of boiling water to cook.