NAH. Her parents are grieving as you are and every person grieves differently. If you would like to pay your respects at Ruby's funeral, please do. Her father may not want you there, but it says more about his grief than his supposed anger towards you. At the moment, you are the easiest target for his emotions.

Side note: Having read this post and your r/tifu post, I think you shouldn't blame yourself; although, I know it's easier said than done. You really don't know what was going through Ruby's mind in her last days. Please know that as a landlord, you cared enough that you noticed her when there was no response. It's unfortunate, but there are other shittier landlords who wouldn't have cared at all.