It would appear that John McMullen was still alive in 1870
1870 Beat 5, Leon, TX Mc Mullin, John 45 ALA Catharine 44 ALA W. A. 21 MS - male - (Willis) B. F. 16 ALA - male M. E. 14 TX - female I or J. M. 13 TX - female S. J. 7 TX - female - (Sarah md Paine) N. B. 5 TX - male - (Napoleon)
I've found Catherine in 1850, 1870, 1880, & 1900.Haven't found her in 1860.Any idea where they were then?
Every reference to John's birthplace, with the exception of the 1850 census is either ALA or MS, by both Catherine & Kids.
I'd bet that Catherine & Elizabeth were sisters - children of William Basket b. NC and Catherine B. SC - In Lauderdale 1850 census.Unless there is a surviving will, probate, or land records for William you likely won't be able to prove it though.