What can be done to get the Comptroller's office to release the funds to my mother?

Wills normally can't be probated after four years, under Texas Law. However, the courts will make some exceptions. Your best bet is to consult with an attorney in your area who focuses on probate law. That attorney is likely to know if you'll have success probating the will. Also, there are alternatives to probating the will that may be easier and more affordable. The probate attorney can also discuss those alternatives with you. Many probate attorneys in this area offer free consultations. I'd take advantage of that to find out what your options are. I'd do it soon, too, since you don't want that money to escheat.

Unless your situation falls under certain exceptions, a will must be probated within four days of the date of death. You may have other options to probate the estate, such as a small estate affidavit or determination of heirship proceeding. Speak with an probate attorney in your area to discuss what options are most appropriate for your situation. Good luck to you.

You should consult with a probate attorney. I agree with the other attorney that it is likely that a small estates affidavit and order by the court entering it, together with the a certified copy the death certificate and properly completely claim to the comptroller, will get the shares to the right party. You can begin the claim process online with the comptroller's office. The process takes some time, though, so be prepared. Could take more than 6 months.

The other option you might consider is to probate your father's will as a "muniment of title." Usually when you probate a will, someone is appointed as the executor and they have a list of duties (including paying final expenses and dealing with creditors). When you probate a will as a muniment of title, you still go through the local county court, but instead of asking to have someone authorized to speak for the estate, you're just asking for the will to be recorded to show the passing of assets from the person who died to the person who was (or people who were) listed as beneficiaries. There's no executor appointed and no authority to act on behalf of the estate; however, the will is officially recognized by the court as the deceased person's final will and testament, which allows others to deal with the beneficiaries as owners of the property. In our county, our courts are more willing to allow a will to be probated as a muniment of title after the 4 year limit -- especially if you can give them a reason why. (I've probated one this way because the original will was packed up and lost in a box of pots and pans for years.) Check with the Texas Comptroller through its website: https://mycpa.cpa.state.tx.us/up/Search.jsp and check with a local probate attorney who can help check with the local court to see if they would be ok with treating this as a muniment of title.