YOU SAID:
my mother went to the supermarket to buy eggs
INTO JAPANESE
母は卵を買いにスーパーへ行きました
BACK INTO ENGLISH
My mother went to the supermarket to buy eggs.
INTO JAPANESE
母はスーパーへ卵を買いに行きました。
BACK INTO ENGLISH
My mother went to the supermarket to buy eggs.
That didn't even make that much sense in English.