Mother in-law is 86 and has limited mobility. Any help?

I am the father of the groom and my wife's mother has limited mobility. this issue is my wife's brother and sister are reluctant to take care of her and is leaving it up to my wife to organize her transport to and from the venue. this is causing stress on my wife as we are part of the wedding party and won't have time to look after her. my brother in law and sister in law will also have additional 4 daughters and partners. are there any specialised services they we could use to help out.