So, lets see what Ketu can do in 4th house without any conjunction or aspect from any other planet. 1st lets see what these 2 things represent -

Just like Rahu, Ketu also represents illusion as both are illusionary planets but the difference is that Ketu is also the one who removes the illusion and brings enlightenment. Besides this, Ketu represents isolation, separation, spirituality,mystical world, other dimension means things related to alien world, also represents Son, Dog, Intuition, research ability, curious nature, things which we have already achieved in past life and not much concerned to perform in this life.

4th house represents your home, home environment, homeland, mother, nourishment, childhood friends, peace of mind, conveniences, intuition etc.

Aspect-wise, in Vedic Astrology, Ketu has 5th and 9th house aspect. He is unable to impact 7th house from its place as Rahu is sitting there, which is the other axis of Ketu and represents all those things which are non-Ketu. Although Ketu represents isolation and separation, but interestingly its aspects never isolate and separate a person from the things represented by house it is aspecting. Ketu only makes a person curious and research oriented and motivates a person to research about it.

So, when Ketu comes in 4th house, 1st of all it gives a feeling of isolation from mother. Mother may be physically isolated from the person or person always feels that his mother is not fair to him. He feels that his mother neglected him in giving love. These people stay away from their homeland most of the time. They are also separated from their mother. If mother stays with the person, then in 90% cases, her health suffers. They have high intuitive powers. This position separates them from their homeland and sends to foreign land. These people may not have home property in their name, else they will not be able to stay in that home. Most importantly, this is 1st of the Moksha-Margi position which leads to ultimate liberation of soul. Houses number 4, 8 and 12 are known as Moksha houses. Ketu represents final liberation. So, whenever Ketu comes in either of these houses, these people seek the truth of life and look for liberation of soul from the rounds of birth/death.

From 4th house, Ketu aspects the 8th house of occult, hidden secrets etc and 12th house of spirituality. All the houses involved are moksha margi hence spirituality becomes a huge thing here. They need to educate themselves about spiritual and occult side of life to get their peace of mind.