Identify the correct sentence.
a. whenever we go to grandma's house, we play scrabble.
b. whenever we go to grandma's house, we play scrabble.
c. whenever we go to grandma's house, we play scrabble.
d. whenever we go to grandma's house, we play scrabble.

The correct answer here would be 
C. Whenever we go to Grandma's house, we play Scrabble.

The option with both Grandma and Scrabble beginning with a capitalised word.
The reason for this is that Grandma and Scrabble are both proper nouns and proper nouns are always spelt with a capital first letter.
Other examples of proper nouns are George, America, English, Hooter's, etc.