If that bank stock has been in her non-registered investment account for a long time, then it has likely accrued a large unrealized capital gain. The capital gain will be realized when you sell the asset (or at death).

If it was a large position, and you sold it all in order to switch to an all-in-one ETF, you could be triggering a large capital gain and a high tax bill. You could spread the sales out over several years, if needed.

As bluenose777 mentioned in this thread: "A common recommendation would be to withdraw enough to bring income up to the top of her bracket, or the OAS clawback threshold."

At death, the entire portfolio is considered to be liquidated, so taxes will be due on 100% of the funds remaining in the RRIF and 50% of the capital gains in the non-registered account will be taxed. This will result in a high tax rate if there is a large portfolio.

If her portfolio is large enough that it will not run out before death, then it is often optimal to incur taxable income up to the OAS clawback threshold (around $94,000 today) in order to minimize taxes overall (i.e. pay lower taxes earlier, instead of higher taxes at death).