its less than 5 min. walk Millennium Taiba Hotel are the nearest hotel to Bab e Salam gate

Yes they have credit card machine

Sorry for the late answer. I think for your mom, it's not the right hotel.. it is an amazing hotel and right next to door 6 as I remember. But she has to walk a good distance from that door to the area where women can pray, because it's different from Mecca, Women and Men don't pray next to each other. They have separate areas for them. And if she wants to enter the place where nabi Mohammad is, it's also a bit far, because the Mosque is huge. So if your mom is ok to walk for 10 to 12 minutes (Slowly walking I mean) you can take it definitely, but if not, you better find another hotel. All the best. ps: please don't forget Do3a2 for us.