The main character's grandma passed away long time ago at least 20 years ago, and Melinda(the main character) said "She would have been 80.", but didn't she make a mistake in saying "(If she were alive), she would be 80"?
"She would have been 80" is a conditional refering to the counter factual past meaning "If she had been alive back then, she would have been 80". Even if she supposed "if her grandma was alive a few years after she passed away",it won't make sense. From what I watched in the drama, her grandma was like between 60 and 70 when she was a little girl like 7 or 8. and at least twenty years have passed till now.
It's all confusing.
125901 - Is this your grandmother?
127433 - Wow. She looks
127433 - exactly like you.
129368 - In fact, i think i've seen this
129368 - bathing suit in your closet.
131533 - She was very special.
134533 - I miss her.
135800 - Like, "special" special?
140334 - Her birthday is sunday.
140334 - She would have been 80.