Is it permissible for an elderly woman who uses a wheelchair to combine the Dhuhr and Asr prayers with one ablution, and similarly the Maghrib and Isha prayers?

If a woman finds it difficult to perform every prayer at its appointed time, she is permitted to combine the associated prayers (such as Dhuhr with Asr, and Maghrib with Isha) to alleviate hardship and difficulty. There is no objection to performing the prayers with a single ablution.