I am more lonelier (1)/ here than (2)/ I was in the USA. (3)/ No error. (4)

Answer

1

Explanation

more lonely / lonelier will replace more lonelier because-
Use of Double Comparatives is incorrect.
Look at the examples given below :
He ran faster than his friend
He ran more faster than his friend
The very word Comparative means that two objects are being compared againsteach other.
Hence, I am more lonely/lonelieris the right usage .