The VA hospital is located on Fort Harrison, which is approximately 3 miles west of Helena. Here is a link to VA Montana Healthcare System for some further information. You may want to contact the Patient Advocate to receive more specific information.
Also, the Veterans Benefits Administration Regional Office is located on Fort Harrison as well, so if you have any questions regarding his VA service-connected benefits, there is a local office that is available.
I hope this information helps and if you have further questions, please don't hesitate to ask.