I had used the 'wheel-chair' facility for my mom as she needed it. Its awesome.  You can also get assistance without asking for wheel chair as well.

I had also made small cards for my mom to show at the airports where she needed assistance. (My mom knew which ones to show, as I had inscribed in Nepali for her like -yo card dallas airport ma dekhaune)
The note said something like this.
   HELP.
   I do not speak English.
   My name is ..... I am traveling to .... airport please help me locate my flight #....

At one airport they even located an Indian guy after they found out that my mom understands very little hindi to escort my mom to her flight.

You do not need anyone to assist your parents during travel, if you ask for assistance. You can also let the ticket agent know before hand that your parents need assistance, they will also take care of their passengers.

Hope this helps.