She had not a lot of debt and just a couple of credit cards.
Has anything been done about any of these other creditors? its probably just a matter of time before you hear from the other creditors, beside Capital One.
By not opening up probate, eventually all of the creditors will have to be dealt with. All will be able to look online, and determine that Mom had an asset - a house - that can be used to satisfy the debt.
Someone needs to open up probate - which can be done with a small estate affidavit in Texas. The creditors need to be paid. If there was no money in any bank account or any other stock, savings account, etc., the house has to be sold and the proceeds used to pay the creditors.
You will not be able to transfer the car or the house until probate is opened.