You'd need 27 mL of pure methanol to make that solution.
So, you know that you have a stock bottle of liquid methanol. The methanol has a density of 0.793 kg/L, which means that a 1-L bottle will contain 0.793 kg of methanol.
To make the calculations easier, convert the density from kg per liter to g per liter
Now, you know that your target solution has a molarity of 0.25 M and a volume of 2.5 L. This means that you can determine how many moles of methanol the target solution must contain
To determine how many grams of methanol would contain this many moles, use the compound's molar mass
This is how much methanol your target solution must contain. To determine what volume of the pure methanol solution you need to get this many grams, use the given density
So, if you take 27 mL of pure methanol, and add enough water to make a total volume of 2.5 L, you'll end up with a 0.25-M solution.