The best deal for MK is going to be the florida resident 1 day ticket right now since they are residents and I think your visiting when it would be valid. Not sure how a non-resident would purchase them for someone who is a resident so you may need to call or let them purchase them logging into
mde with a florida address on their account as they would appear for online purchase. Generally proof of residency is needed so don't try to slip yourself into the same deal. It'll be 97, 102 or 114 depending on what day they are actually joining you (adult price). Disney has peak pricing for 1 day tickets and per the website in feb there is all 3 peak levels on different days.
You only get a free magicband if staying at a disney resort. They could use a previous trip magicband or just their hard tickets they can pick up on the way into the park. Magicbands are not a requirement. if your seriously considering buying bands for them as well you didn't list how many people are actually coming but it might actually be cheaper or very close to the price to also get them a 1 night stay at a value resort so they don't have to make the 90 minute trip back when exhausted. I think there is a florida resident deal on values right now so it might be cheaper than you think. I want to say 4 people plus parking (they need to pay to park) would be the same price as a value + 4 solid color magic bands and no longer a parking fee.
Also they can't ride anything during Extra magic hours and can't get in early during morning extra magic hours. If your planning to utilize them on the day they are coming, that 1 night stay to get a magicband would make them eligible to be there during emh.