Yellowing and dried leaves can be a sign of several issues for indoor plants. Here are a few common maintance practices to consider:

1. Overwatering: This is the most frequent reason for yellow leaves. Ensure that you're not watering too much, as excess moisture can lead to root rot and stress, causing leaves to yellow and drop off. It's important to check the soil moisture before watering again. Likewise, underwatering can cause the leaves to yellow and dry out.  Be sure to check the moisture level before you water.  Surface soil down to an inch or two should be dry.  After watering, do not let the plant sit in water.  Let them drain well.

2. Nutrient Deficiency: If your plants are not getting enough nutrients, particularly nitrogen, the leaves may begin to yellow. This can happen if the soil lacks nutrients or if the plants have been in the pot too long. Consider using a balanced fertilizer to address any deficiencies. Do not over fertilize during the winter. Often using half strenth will be beneficial. 

3. Environmental Stress: Plants may also experience yellowing due to stress from temperature extremes, insufficient light, or transitioning from one environment to another, such as moving from a greenhouse to a home setting. Your plants seem to have been in the same spot for a while, but the window could be colder in the winter.  Is there a heat outlet close by?  The Peace Lily could use a cleaning to remove all the dead material.  Some of it may pull out or it may be cut.  How long has the plant been in the pot?  It may need repotting.

4. Natural Aging: Sometimes, yellowing leaves are part of the normal aging process, especially if they are older, lower leaves. If the rest of the plant appears healthy, this may not be a concern. Some of this may be going on with the Dracaena. 

Consider examining the watering routine, the soil’s nutritional content, and ensuring your plants are not exposed to drafts or extreme temperatures.  

The following article is a general review of good maintenance practices for house plants.