Is it more appropriate to prioritize serving one's mother over one's wife — by leaving the wife — due to the impossibility of combining both, especially since there are other disputes with the wife, and she is in her 'iddah period after a revocable divorce, and they have two daughters?

The mother's right is great, and honoring her is among the most obligatory duties. Serving and caring for the mother is obligatory upon all her children, either by doing it themselves in turns or by providing someone to serve her. If you care for your mother hoping for reward, then you are a doer of good, and your wife does not have the right to object as long as you do not fall short in her rights. However, she is not obligated to accept living with your mother unless you provide her with a suitable, independent dwelling. A righteous wife should help her husband in honoring his mother. We advise combining the honoring of the mother with maintaining the wife in kindness, and we do not advise divorce unless maintaining the wife leads to neglecting the mother's right and your shortcomings towards her.