Hi and welcome to JA. I am Ray and will be the expert helping you tonight.
I am so sorry for your loss and this situation.
You would have lawyer make application to probate
will in Arkansas and be appointed personal representative.
Once this done a second lawyer with ancillary probate
in Texas is the next step.Once appointed here you have authority to evict her and sell the property.Expect ancillary probate and eviction to take 60 days or so.
This is the procedure when the deceased resided in one state and then had property in a second state.The will and codicil are likely accepted and validated by the court.
You will likely need two lawyers.I would concentrate on one in Arkansas to get this started.The Arkansas lawyer will help you locate a second lawyer in Texas for ancillary probate.
I think it is likely she may contest the codicil here but time will tell whether she does or just doesn't cooperate.
Arkansas lawyer referral with ratings..
As you can see below ancillary is much simpler and shorter here in Texas..
I appreciate the chance to be of service tonight.Please let me know if you have more follow up.Thanks again.