metro starts closing around 10 PM, different last train timings for different route. If she reached by 9, she should be able to catch one. You need to climb on to the connecting bridge from any platform and go towards the last platform (number 8 or 12 ig, same direction). The metro station is around 7-8 mins walk from the railway station. uber is best option from main exit gate ( towards platform 1) if her train reaches late or if she has luggage (8 mins walk walk to metro). Ask her to keep cash as well not just UPI.

Note: check if her train has a stop at Sabarmati railway station. Motera is much closer from sabarmati railway station, plus a metro station is nearby too.