Total attendees = 60

Target question => How many people drink coffee
Let people who drink coffee = c
Let people who do not drink coffee = d
Total attendees = c + d
60 = c + d. Find c

Statement 1 => The number of people at the party who drink coffee is 4 times the number of those who do not drink coffee
c = 4d
From question stem => 60 = c+d where c = 4d
60 = 4d + d
60/5 = 5d/5
d = 12
c = 4d; c = 4 * 12 = 48 people drink coffee. Statement 1 is SUFFICIENT

Statement 2 => The number of people who don't drink coffee is 36 less than the number of people who drink coffee
d = c - 36
From question stem => 60 = c + d when d = c - 36
60 = c + c - 36
60 = 2c - 36
60 + 36 = 96
96/2 = 2c/2
c = 48 people drink coffee. Statement 2 is SUFFICIENT

Since each statement alone is SUFFICIENT
Answer = D