I am sorry to read what you are going through caring for your Mom.
There are many Stage IV survivors here posting every week.
My suggestion is to make sure she gets a second opinion on treatment from a major cancer center if possible. Treatment plans can still be implemented at the local facility as long s the overall plan gets the consent from a major cancer facility.
There is another thread ongoing covering a similar circumstance for KRAS mutant. You may get more reading those posts as well.
D/H 47 years old, 10/2014, Stage IV M/CRC, nodes 12/15, para-aortic, 5 cm sigmoid resection, positive Virchow. KRAS mut, MSS, Highly Differentiated, Lynch Neg, 5FU/LV and Avastin 1 YR (Oxi for 5 months), Zeloda/Bev since 01/2016. 02/2019 recurrence para-nodes, back to 5FU/LV Oxy/Bev. It is working again. "...Perseverance is not a long race; it is many short races one after the other."-Walter Elliot