I'm thinking of you and your Mum. We too have been down the recurrence road. I was terrified. Kris had his recurrence 10 months post rads and chemo. Most recurrences ocur within the first 12 months. I'm not sure where your Mums tumor is, so can't guess on what surgery they will offer. My advice is to treat this aggressively. If the surgery sounds outlandish, do it. I have seen a few on this board who have refused surgery due to what they quote as too severe quality of life effects. Not 1 is still around to post. Kris had very drastic surgery and here he is , alive and well 3 years later.
Keeping you both in my thoughts and prayers.
Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!