This is not correct. Mormon funerals are not held at a temple, and anyone can attend.
They had some sort of deal for her the next morning that we were not invited to, the announcement was directed at the LDS members. I have no idea what it was, I was not invited, nor was the rest of the family or friends that were not LDS. Her own daughters that were not LDS were not invited.
I have had LDS tell me before that is not how it is done but that is how it was done. It may not have been an LDS thing- her husband may have planned it that way for all I know. I don’t know much about the LDS...more than some but still very little.