When my wife makes almond roca, just as the ingredients are approaching hard crack stage, the butter and sugar separate causing a grainy consistency.

Are you adding a tablespoon of corn syrup? It prevents seizing up and grainy texture.

Why is my almond roca separating when I cut it?? The chocolate separates from the toffee!! This has never happened to me before!!!

Jimmyray, here's the recipe I use. I've made it hundreds of times.

Almond Roca Toffee 
 
 3 cups sliced almonds, divided
 4 sticks (1 pound or 2 cups) unsalted butter
 3/4 cup water
 1 teaspoon salt
 scant 2 cups granulated sugar (I use 390 grams worth)
 2 Tablesoons light corn syrup
 1 teaspoon baking soda
 12 ounces fine quality milk chocolate, chopped ( I use Hershey's Special Dark Chocolate bars) 
 
 Preheat oven to 350 degrees
 
 Evenly spread 1 cup sliced almonds onto a baking sheet and place in the oven until they turn a light brown, stirring occasionally, about 6-8 minutes. Remove from the oven and allow to cool. Slightly crush almonds. Set aside remaining almonds for use later on.
 
 Cover a 10" X 15" baking pan with foil and set aside.
 
 Place butter, water and salt in a large heavy bottomed saucepan. Place over medium heat and cook, stirring occasionally, until the butter has melted. Stir in sugar and Golden Syrup (or corn syrup). Attach a candy thermometer inside the pan and leave the heat on medium. Bring mixture to a boil and cook, without stirring, until the temperature reaches 240 degrees. Stir in the remaining 2 cups almonds. Keep stirring until the temperature reaches 295 to 300 degrees.
 
 Remove pan from the heat and carefully stir in baking soda. Working quickly, pour mixture into the prepared pan, gently pushing hot candy into the corners with a heat-safe spatula if needed. This will begin to set very fast so don't mess around too much.
 
 Wait 5 minutes, then sprinkle chopped chocolate over the top of the candy and let sit for 5 more minutes. Using a small off-set spatula, spread the softened chocolate evenly over the top. Sprinkle with the crushed almonds and let cool at room temperature for about 60 minutes. Place in the refrigerator and let sit until the chocolate has set. Break into chunks with a knife or your hands.
 
 Makes about 3 1/2 pound 

I make a lot of toffee, and I cook on medium heat. Is she using a different stove this year? If you want to post her recipe and method that would help. Last week I made 24 batches of almond roca toffee!

Is she using the same pot she always did? Read about toffee separating and the causes. There are questions here about it already as it has likely happened to many candy makers on occasion. First heat everything gently to start. Do not have sudden variations in temperature high or low. /Seems boiling off the water quickly can destabilize it. Using salted butter or adding 1/4 tsp per stick helps with stabilizing, it seems. Use a heavy pot to help regulate the temperature and prevent hot spots. If the recipe calls for stirring, stir gently.

prior discussion
https://food52.com/hotline/17099-why-does-toffee-separate