Floored by initial diagnosis

After weeks of tests and suspected lymphoma my mother has today been told she has cancer above the jaw meaning somewhere in her head. She has pain/ swelling in her lymph nodes in her neck which is causing her discomfort eating - we are told is a result of the cancer somewhere else and it is definitely not in the lymph nodes. I feel absolutely desperately sad and scared for the future. My poor mum doesn’t have a wide support network and I live 200 miles away and have young children. I visit as often as possible but I feel so far away and like I’m letting her down. We have more tests to follow to locate the cancer - mri, PET and endoscopy and it is totally overwhelming. I would hugely appreciate any advice for supporting my mum in the best way. I can’t imagine how frightening it must be for her. Thanks in advance x