Texas distressed grandparents

Our daughter divorced after 2 years and 2 wonderful grandsons, now age 5 and 3. Her ex has never seen the 4 year old until last month when he suddenly became interested in his "rights" so see the children and have them for 30 days during the summer. He has never voluntarily paid anything, support or otherwise. He has them now and is supposed to return them home to her but he claims he doesn't have gas money. He just wrecked his care (kids onboard = they are OK). He had a rental car when he picked them up but says it had to go back. Only support was from garnishing his wages which was very minimal, less than $1500 in 5 years. He goes out of state to work so garnishment won't apply, when in state he is on unemployment or leaching from his relatives. What can be done? Our daughter claims nothing can be done, even though the kids return home saying they aren't fed enough or allowed outside to play. Are there any support groups out there in Texas?? any suggestions appreciated