I think walking is wonderful and love that your mom is excited.
My daughter has walked with a school group. They stay overnight...so along with chairs...she also took her sleeping bag and a pillow...others had brought large tents that slept 6 - 8....oh and a roll of TOILET PAPER. Facilities were porta potties...and subject to running out of paper.
The group got together and individuals volunteered what food items they would bring. Every meal was covered this way. Some brought long folding tables, some coolers, and another a grill.
The walk is held...regardless of rain. Take rain gear or pick up ponchos at the dollar store.
As sladesmom said...there are groups that will have things to purchase...so you might want to take a little spending money
There are events around the clock...some themed. Like one walk...was a hawaiian theme...one a beach...you'll have to look at your home site to find out if they're doing these I guess...then bring the appropriate attire or accessories.
Have fun and good luck!!