Okay, let's fill in the blanks with the correct forms of the verbs:
My grandmother usually cooks for the family, but today it is her birthday.
Explanation: Here we use the Present Continuous ("is being") because it's referring to something that is happening today, at the moment of speaking. But the "be" verb is used here in Present Simple.
so I am planning a special meal for everybody.
Explanation: Present Continuous ("am planning") is used to describe an action that is happening now or around now.
My grandmother loves meat, so I am making some delicious meat pies.
Explanation: "Loves" is in Simple Present to describe a general truth or a habit. "Am making" is in Present Continuous because it's happening now.
My father hates meat, though, so I am preparing a nice salad for him.
Explanation: "Hates" is in Simple Present to describe a general truth or a habit. "Am preparing" is in Present Continuous because it's happening now.