A month is not at all unreasonable for turnaround time. 6 weeks is also reasonable, or 2 months, or even longer if the longarmer has a backlog of quilts, and many do. On the longarming forums I've heard some longarmers start to fret when their backlog is only one month long.
What is not reasonable is that you were given one time, and not notified when it couldn't be met, and this seems to be a pattern. Perhaps she accepts quilts from guild members at a discount and therefore feels that she can put them off and do the quilts for her full-price customers first? That would be a reasonable policy if it's clearly stated to the guild members that they will have to wait. Or is she perhaps not doing the longarming as a business, but just doing quilts for friends when she has time? Has she had personal or family health or other problems that made it impossible to meet her commitments? Is she just late in doing everything in life? Whatever the reason, it seems clear that you will need to either find another longarmer who can meet your schedule, or plan to wait until this lady finishes your quilts.