Apparently, swelling of legs/ankles can be linked to anaemia (which can be caused by chemo and other things too). Might be worth asking about blood results (haemoglobin).
Welcome to the forums, I'm sorry to read about you're Mums diagnosis and the problems she is experiencing. Whilst you are waiting for the other users to reply with knowledge and support you might find it helpful to talk things through with a member of staff on the helpline. Here you can share your thoughts and concerns with someone who will offer you a listening ear as well as emotional support and practical information. The number to call is 0808 800 6000 and lines are open weekdays 9 to 5pm and Saturday 10 to 2pm.
Best wishes Sam, BCC Facilitator